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I've been wanting to try this in place of 1 player at a time doing 4 phases consecutively.

Players roll off for Go first, go Second to determine who moves or acts first in the event of an initiative tie.
During each phase both players move,psychic, shoot and assault by Units Initiative.
I.e. Movement phase: Player 1 (go first) moves 1 initiative7 unit. Player 2 moves 1 init7 unit. Repeat until all Initiative 7s have moved. Begin Initiative 6 moves.
Apply this to all phases.

This would allow a more Real time play enabling both players to be active instead of 1 watching and waiting.
On the downside it requires more knowledge of your own army to prevent errors in play.

This would basically ensure the Eldar always go first and Necrons go last. Eldar don't need more help. I think a better system would be alternating phases. (Player 1 movement phase, Player 2 movement phase, Player 1 psychic phase, Player 2 psychic phase, etc. etc.)

 EnTyme wrote:
This would basically ensure the Eldar always go first and Necrons go last. Eldar don't need more help. I think a better system would be alternating phases. (Player 1 movement phase, Player 2 movement phase, Player 1 psychic phase, Player 2 psychic phase, etc. etc.)

Good point, i like that idea too.
I think they're crazy when they say 2+armor and things like twinlinked and they look at me like I'm insane when I say no armor whatsoever and I completely ignore terrain or 36inch turboboost. So I'm not looking for any advantage just increased game speed. I just tend to forget people have horrible initiatives until they charge me and die before getting to swing back lol

Oh, I didn't think you were trying to gain an advantage or anything. I figured you were just looking at the system through the lens of your army. It's what makes balance so tough in a game like this. Something that works great when comparing Space Marines and Tau, for example, falls apart when applied to Tyranids vs. Space Wolves. I definitely agree, though. It sucks to have to sit and wait for your opponent's full turn completely unable to adapt to the situation the way a real army would.

I suggest trying a few games with alternating unit activation. Players take turns activating a unit and carrying out all phases (move, shoot, assault) with that unit. It works much better than you'd expect, with a few small tweaks.

A friend and I played alternating units. For each unit you put a dice in a bag and the other player the same but a different colour. You take turns pulling a random dice from the bag. You can only activate each unit once and you move shoot and charge on each unit individually. Makes for a more reactive game. You need to think about what units you want to activate and when.

I like to put every new rule idea to the "Ork Test". If the new rule can work for Orks then its worth looking into further. If the rule falls apart for Orks then its probably not a very good rule. All the BS modifiers threads or having cover saves be in addition to armor saves tend to fall apart when you look at how it impacts BS2 and 6+ armor Orks compared to say BS4 and 3+ armor Space Marines. That being said this change would hurt Orks given their rather poor initiative so they basically never go first against most armies and its easier to shoot them off the table as they at best get to go before Tau and Necrons (Nobz being I3) but behind everyone else. This also fails on the "Eldar Test" as anything that makes Eldar even more power is generally not a good thing for the game. This makes the Eldar stronger (just imagine how brokenly OP battle focus would be with this rule).

 CalgarsPimpHand wrote:
I suggest trying a few games with alternating unit activation. Players take turns activating a unit and carrying out all phases (move, shoot, assault) with that unit. It works much better than you'd expect, with a few small tweaks.

I have tried alternating activations before. It's better than the vanilla alternating turns, but it still feels odd, like both armies are standing around waiting patiently while a single unit moves forward, shoots at the enemy, and then charges said enemy and only then reacting.

I really think that alternating phases is the way to go. Alternating activation and letting units go through all of the phases just really doesn't compute for me

I have to say my experience with alternating unit activation , has had similar objections that EnTyme posted above.(You are NOT in a minority! )

I believe the best option for simultaneous resolution in 40k, is to use Alternating phases, but leave casualty removal unit until both sides have made their attacks.

EG
Player A moves.
Player B moves,

Player A shoots and marks casualties.
Player B shoots and marks casualties.
Players remove casualties.

Player A Assaults and marks casualties.
Player B assaults and marks casualties.
Players remove casualties.

(Players can alternate going first each turn or roll off to chose if they want to.)

Lanrak wrote:
I have to say my experience with alternating unit activation , has had similar objections that EnTyme posted above.(You are NOT in a minority! )

I believe the best option for simultaneous resolution in 40k, is to use Alternating phases, but leave casualty removal unit until both sides have made their attacks.

EG
Player A moves.
Player B moves,

Player A shoots and marks casualties.
Player B shoots and marks casualties.
Players remove casualties.

Player A Assaults and marks casualties.
Player B assaults and marks casualties.
Players remove casualties.

(Players can alternate going first each turn or roll off to chose if they want to.)

Seems like a lot of book keeping and it makes the whole "remove the closest models" and sniping out characters in general more complicated. Again there are rules like battle focus or thrust move that would be a nightmare to play against when you don't have a movement phase to react to a movement action made during a different phase.

@Vankraken.
Sorry I assumed we we talking about a complete re-write to correct all the issues in the core rules.

 Vankraken wrote:
I like to put every new rule idea to the "Ork Test". If the new rule can work for Orks then its worth looking into further. If the rule falls apart for Orks then its probably not a very good rule. All the BS modifiers threads or having cover saves be in addition to armor saves tend to fall apart when you look at how it impacts BS2 and 6+ armor Orks compared to say BS4 and 3+ armor Space Marines. That being said this change would hurt Orks given their rather poor initiative so they basically never go first against most armies and its easier to shoot them off the table as they at best get to go before Tau and Necrons (Nobz being I3) but behind everyone else. This also fails on the "Eldar Test" as anything that makes Eldar even more power is generally not a good thing for the game. This makes the Eldar stronger (just imagine how brokenly OP battle focus would be with this rule).

And what if its not designed for Orks then?

Lanrak wrote:
I have to say my experience with alternating unit activation , has had similar objections that EnTyme posted above.(You are NOT in a minority! )

I believe the best option for simultaneous resolution in 40k, is to use Alternating phases, but leave casualty removal unit until both sides have made their attacks.

EG
Player A moves.
Player B moves,

Player A shoots and marks casualties.
Player B shoots and marks casualties.
Players remove casualties.

Player A Assaults and marks casualties.
Player B assaults and marks casualties.
Players remove casualties.

(Players can alternate going first each turn or roll off to chose if they want to.)

I think we're getting closer here, but I'm not sure how I feel about leaving casualty removal until in the end of the phase. That seems like it weakens the impact of an attack. I would suggest using Initiative to determine the order in which shooting is resolved, but then we are back to the initial problem of the system favoring Eldar and DE and making Necrons and Orks basically cannon fodder (Orks more so since my Necrons could probably RP their way through the first 7 initiative steps).

The problem with "simultaneous" turns is that such systems strongly favor MSU armies and hurts assault armies a lot. Each time an assault unit moves towards an intended target, the other other player just moves the intended target away. After all the first player's units have acted, the MSU player still has units left over that can act and actually do damage.

Alternating turns could be interesting though.

Regardless of what system you go with, favoring higher initiative probably isn't the way to go.

Won't it cause a strange game with all the marks? I guess you can't cover the board with marks, so you'll probably want to lay down the models which are casualties, which also will cause a strange game (in my opinion, of course) as one player have to make shooting attacks with models which lie down.

Objecting to units acting one at a time (alternating activations, carrying out a complete turn with each unit) seems kind of silly when so many other games do it - like, the majority of recent war games. But to each their own.

Alternating phases isnt really a great idea, as I've said in the past. On its own it doesn't solve any problems other than reducing downtime, and it causes some problems of its own.

For starters, you've still got the issue of alpha strikes, unless as Lanrak said, you mark casualties as you go and remove at the end of the combined phase, so your bookkeeping has gone way up.

As EnTyme said, you also make it incredibly easy for Player B to kite Player A if you want to avoid close combat - Player B can react perfectly to Player A's movements to stay out of charge range. Player B also has the advantage in positioning perfectly for shooting (either to avoid fire or get into position).

So you could go back to letting Player B take damage first instead of marking it, but now you strongly favor shooting, because close combat is still easier to avoid, while shooting alpha strikes are still a risk.

Stuff like this is why you rarely see alternating phases in games. Alternating activation isn't as intuitive in terms of "simulating" what's happening, but it works infinitely better as an actual game mechanic.

Plus I think you can use it almost directly in 40k without rewriting many rules. Balance is another issue.

 CalgarsPimpHand wrote:
Objecting to units acting one at a time (alternating activations, carrying out a complete turn with each unit) seems kind of silly when so many other games do it - like, the majority of recent war games. But to each their own.

Alternating phases isnt really a great idea, as I've said in the past. On its own it doesn't solve any problems other than reducing downtime, and it causes some problems of its own.

For starters, you've still got the issue of alpha strikes, unless as Lanrak said, you mark casualties as you go and remove at the end of the combined phase, so your bookkeeping has gone way up.

As EnTyme said, you also make it incredibly easy for Player B to kite Player A if you want to avoid close combat - Player B can react perfectly to Player A's movements to stay out of charge range. Player B also has the advantage in positioning perfectly for shooting (either to avoid fire or get into position).

So you could go back to letting Player B take damage first instead of marking it, but now you strongly favor shooting, because close combat is still easier to avoid, while shooting alpha strikes are still a risk.

Stuff like this is why you rarely see alternating phases in games. Alternating activation isn't as intuitive in terms of "simulating" what's happening, but it works infinitely better as an actual game mechanic.

Plus I think you can use it almost directly in 40k without rewriting many rules. Balance is another issue.

As someone else noted, though, Alternating Activation heavily favors MSU armies. If Player A is using a low model count army like GK and Player B is using a horde army like Tyranids, then Player A is going to sit around doing nothing for half the turn while Player B is activating the remainder of his army. Not that Tyranids couldn't use a little boost, but this doesn't seem like much fun to me. I've seen and used Alternate Activation in 40k before, and it just doesn't work as well as people claim it does.

As to your point about the ability to kite CC armies, that is a definite concern, but the ability to react to your opponent's actions more effectively is the entire point of alternating phases. It makes the game more tactical. It encourages strategies like flanking your opponent to force them into CC range as opposed to just charging down the middle of the board with you TWF (who would honestly catch pretty much anything trying to kite them anyway).

 EnTyme wrote:

Spoiler:

 CalgarsPimpHand wrote:
Objecting to units acting one at a time (alternating activations, carrying out a complete turn with each unit) seems kind of silly when so many other games do it - like, the majority of recent war games. But to each their own.

Alternating phases isnt really a great idea, as I've said in the past. On its own it doesn't solve any problems other than reducing downtime, and it causes some problems of its own.

For starters, you've still got the issue of alpha strikes, unless as Lanrak said, you mark casualties as you go and remove at the end of the combined phase, so your bookkeeping has gone way up.

As EnTyme said, you also make it incredibly easy for Player B to kite Player A if you want to avoid close combat - Player B can react perfectly to Player A's movements to stay out of charge range. Player B also has the advantage in positioning perfectly for shooting (either to avoid fire or get into position).

So you could go back to letting Player B take damage first instead of marking it, but now you strongly favor shooting, because close combat is still easier to avoid, while shooting alpha strikes are still a risk.

Stuff like this is why you rarely see alternating phases in games. Alternating activation isn't as intuitive in terms of "simulating" what's happening, but it works infinitely better as an actual game mechanic.

Plus I think you can use it almost directly in 40k without rewriting many rules. Balance is another issue.

As someone else noted, though, Alternating Activation heavily favors MSU armies. If Player A is using a low model count army like GK and Player B is using a horde army like Tyranids, then Player A is going to sit around doing nothing for half the turn while Player B is activating the remainder of his army. Not that Tyranids couldn't use a little boost, but this doesn't seem like much fun to me. I've seen and used Alternate Activation in 40k before, and it just doesn't work as well as people claim it does.

As to your point about the ability to kite CC armies, that is a definite concern, but the ability to react to your opponent's actions more effectively is the entire point of alternating phases. It makes the game more tactical. It encourages strategies like flanking your opponent to force them into CC range as opposed to just charging down the middle of the board with you TWF (who would honestly catch pretty much anything trying to kite them anyway).

Alternating Activation does favor MSU to some extent (I'll discuss the weak points of that strategy in a minute), but there are ways to mitigate it. Epic's blast marker system encourages a mix of small and large formations with a reasonable number of activations on both sides (and the army lists are written to support that). Dropzone Commander groups your units into roughly similar number of formations that are activated together.

The system I would use for 40k is the dice bag system from Bolt Action, where you draw colored dice to see who gets to activate their next unit. It makes it likely the outnumbered player will have activations spread throughout the turn. It also makes it uncertain who will get the next activation so a MSU player can't rely on having multiple activations in a row. And it doesn't require any rules changes.

MSU has its weaknesses too. Spamming small weak units is discouraged in extreme cases because extremely fragile units can generally be broken, crippled, or wiped out in a single activation by a larger unit. You risk losing units completely in a mini alpha strike before you can even activate them, while the other player's stronger units are generally able to weather several of your weaker activations without being reduced down too much. So there is a built in limiting factor, and something like a dice bag system helps too.

So yeah it's a problem, but not really a big one.

For your second point, yes reacting to your opponent is the main point of alternating activations. But there's a world of difference between the two systems we're discussing. If you alternate activations, your opponent activates a unit, that unit actually accomplishes something, and you responding to that development with an activation of your own. There's a sort of natural thrust-counterthrust going on, there are feints and misdirections as you try to hide your overall plan. Each unit gets a chance to carry out the actions you intend, and then your opponent gets to respond in kind.

If you alternate phases, one player telegraphs their moves and the other player responds with perfect information to avoid a charge, or stymie their shooting, or set up perfect line of sight on a unit trying to hide. It's reacting to your opponent to the worst degree, and only one player gets to do it every turn. It doesn't really encourage tactical play at all when one player's tactics are completely transparent, reacted to and possibly nullified by the second player on "tactics easy mode" before they even get to the damage dealing phase. It isn't fluid, it doesn't make real-world sense, and it doesn't make for a fun game, which is the whole point of this.

 CalgarsPimpHand wrote:
Alternating Activation does favor MSU to some extent (I'll discuss the weak points of that strategy in a minute), but there are ways to mitigate it. Epic's blast marker system encourages a mix of small and large formations with a reasonable number of activations on both sides (and the army lists are written to support that). Dropzone Commander groups your units into roughly similar number of formations that are activated together.

The system I would use for 40k is the dice bag system from Bolt Action, where you draw colored dice to see who gets to activate their next unit. It makes it likely the outnumbered player will have activations spread throughout the turn. It also makes it uncertain who will get the next activation so a MSU player can't rely on having multiple activations in a row. And it doesn't require any rules changes.

MSU has its weaknesses too. Spamming small weak units is discouraged in extreme cases because extremely fragile units can generally be broken, crippled, or wiped out in a single activation by a larger unit. You risk losing units completely in a mini alpha strike before you can even activate them, while the other player's stronger units are generally able to weather several of your weaker activations without being reduced down too much. So there is a built in limiting factor, and something like a dice bag system helps too.

So yeah it's a problem, but not really a big one.

For your second point, yes reacting to your opponent is the main point of alternating activations. But there's a world of difference between the two systems we're discussing. If you alternate activations, your opponent activates a unit, that unit actually accomplishes something, and you responding to that development with an activation of your own. There's a sort of natural thrust-counterthrust going on, there are feints and misdirections as you try to hide your overall plan. Each unit gets a chance to carry out the actions you intend, and then your opponent gets to respond in kind.

If you alternate phases, one player telegraphs their moves and the other player responds with perfect information to avoid a charge, or stymie their shooting, or set up perfect line of sight on a unit trying to hide. It's reacting to your opponent to the worst degree, and only one player gets to do it every turn. It doesn't really encourage tactical play at all when one player's tactics are completely transparent, reacted to and possibly nullified by the second player on "tactics easy mode" before they even get to the damage dealing phase. It isn't fluid, it doesn't make real-world sense, and it doesn't make for a fun game, which is the whole point of this.

The dice from a bag option does a little better to balance it out, but now we're talking about yet another layer of randomness taking away from strategy. As far as Dropzone Commander grouping you into similar numbers of formations, do we really need more limitations on what makes a viable build? If anything we should be allowing more options when it comes to army building. 40k just isn't balanced for alternating activations. Maybe it would work after a complete rules rewrite, but I would prefer something that could work with the current system. It seems we'll have to agree to disagree on the merits of Alternating Activation vs. Alternating Phases.

I think an interesting idea might be to do unit activation similar to how Dust does it.

Player A: Activates a unit, moves, shoots, and assaults with the unit.

Player B: Activates a unit, moves, shoots, and assaults with the unit.

*repeat till all units are activated, new turn begins*

HI folks just to clear somthing up right at the stsrt.

Alternating game turns works fine for rule sets written specifically for them.(K.o.W, F.o.W. etc.)

Alternating unit activation game turns works fine for rule set written specifically for them.( Epic Space Marine, Bolt Action etc.)

Alternating phase game turn works fine for rule sets written specifically for them.(LoTR, Firefly , Challenger etc.)

Variable bound game turn works fine for rule sets written specifically for them.(Blood Bowl, Crossfire. etc.)

The variety in size ,availability and in game effect the current units found in 40k .Make current 40k units unsuitable for alternating unit activation, If you want to arrive at a level of balance that is obvious to all players.

All the rules sets that use alternating unit activation with current range of 40k units that I have seen.
Have had to adjust unit composition to balance them , and/or add additional reaction rules.

(Most players are not fond of Death star units decimating large chunks of their army , while they just stand and watch.So they ask for reaction rules like over watch. )

The alternating game phase works well with current 40k units, and has been used in lots of home brew re-writes for the last eight years to great effect.

I am aware you need the re=write the rules completely to sort out all the issues with 40k.

But , alternating phases lets you get there with a minimum of fuss , and keeps the phases 40k players are familiar with.
(And the action phases are one of the things that 40k players in general , think are core elements of '40k ness' in the rules. )

Alternating unit activation can work in a 40k re-write, but takes more effort in balancing unit effects, and the extra rules to cover reactions can add extra complication.

I must admit I misread the title of the thread.

I thought the OP was looking for the simplest and most effective way of modelling simultaneous resolution of combat.

That I why I suggested leaving casualty removal until both players have made their attacks, using alternating phase game turn.
.
(We simply use a 'damage dice' , usually a red D10 or D20, next to the damaged unit showing how many wounds the unit has suffered.This makes it easy to see who has won the assault and how many models are to be removed etc.)

Well, I'll say one thing, and then I'll leave it for the next time this topic comes up and Lanrak and I inevitably butt heads!

Lanrak wrote:The variety in size ,availability and in game effect the current units found in 40k .Make current 40k units unsuitable for alternating unit activation, If you want to arrive at a level of balance that is obvious to all players.

All the rules sets that use alternating unit activation with current range of 40k units that I have seen.
Have had to adjust unit composition to balance them , and/or add additional reaction rules.

(Most players are not fond of Death star units decimating large chunks of their army , while they just stand and watch.So they ask for reaction rules like over watch. )

You mention this every time this comes up, and it's entirely untrue. Epic: Armageddon has units that range in size from a 100 point formation of four Imperial Guard Sentinels to 1000+ point titans, and it works just fine. There's nothing about large disparities in unit strengths causes problems in alternating activation game systems.

There is an inherent balance somewhere between having big units that are hard to shift (but few activations), and small units that are easily destroyed (but provide more activations). This is why army composition in E:A is usually varied, and ideally armies try to include a mix of large and small formations to have a mix of durabiity and flexibility. Note again, there is no issue with mixing very powerful and very weak units inan alternating activation game, and the meta even encourages it.

Things like Overwatch and suppressing units through blast markers can adjust the balance of that meta (and they adjust it towards deathstars and away from MSU spam, so you have that backwards). Ultimately aren't necessary for the game to function, they merely shift the army composition meta.

Since all these ideas throw any existing balance out the window, I don't think that's a meaningful point to make. Any major changes like this we're suggesting require serious errata.

So enough of this nonsense about the impossibility of an alternating activation game with 40k's diversity in unit size. It's simply not true.

You like alternating phases; I think it has fundamental flaws as a concept and doesn't solve 40k's problems. I like alternating activations; you can come up with other reasons to dislike it, but "it could never work in 40k!" isn't a reasonable one.

"it could never work in 40k!" isn't a reasonable one.

Change it to "it can never work in existing 40k without re-writing the rules from scratch"

Also a unit activation by Ini can work fine, if all units in the game a re-writen to match the system.


For 40k, I would prefer to keep the phases and just add more reactions to the game (not just overwatch, intercept and strike back in combat) to have the possibilities for more Player interaction.
Just because there are a lot of other Games that use different systems and the phases make 40k pretty unique.
(otherwise there would be no reason to just skip the 40k rules and use the modesl for SST, Warpath, Gates of Antares etc)

 kodos wrote:

"it could never work in 40k!" isn't a reasonable one.

Change it to "it can never work in existing 40k without re-writing the rules from scratch"

Also a unit activation by Ini can work fine, if all units in the game a re-writen to match the system.


For 40k, I would prefer to keep the phases and just add more reactions to the game (not just overwatch, intercept and strike back in combat) to have the possibilities for more Player interaction.
Just because there are a lot of other Games that use different systems and the phases make 40k pretty unique.
(otherwise there would be no reason to just skip the 40k rules and use the modesl for SST, Warpath, Gates of Antares etc)

I love the idea of more interactions. One I've always considered is an optional move instead of overwatch like retreating.
Or after being targeted twice in 1 shooting face you can roll for "displacing"

I am still testing things but the latest draft removed the common existing "reactions" and replaced them with

Return Fire, Counter Attack, Counter Charge and Retreat.

And it is possible to react to every action of the enemy in a specific range (e.g. getting shot at close range allows you to retreat)

@CalgarsPimpHand.
Do you actually bother reading what I write , or do you simply assume I do not agree with you so you have the right to totally misquote me?

Please direct me to where I posted "it could never work in 40k!"

As Epic has ALWAYS use alternating unit activation over the 4 editions of the game, the rules have ALWAYS been written with this game turn in mind.And so ALL the units used in Epic are developed and balanced with this game turn in mind.

Epic also has the major advantage of being at an appropriate scale for the size of the game, and so allows tactical maneuver to be part of the game play.

Also Epics minature scale means the Epic players are happy with a higher level of abstraction required for this size game.

3 things the 40k game does not have...

My actual points against alternating unit activation in 40k are.
a)It will take far more effort in terms of getting it to work to a level acceptable to the majority of players,with current 40k units.Compared to alternating phase game turn.

B)It will require additional levels of complication compared to alternating phase game turn.

C)It can not be used to model simultaneous interaction like alternating phases can.(If you wanted this.)

D)40k players are familiar with the 'action phases', and are much more receptive to alternating phase game turn that keeps them , than alternating unit activation which is completely new/different.

@Kodos.
Do you do realize that an alternating phase game turn based rule set written with a tactical structure , can cover all these 'reactions' as part of the normal game play?

 kodos wrote:
I am still testing things but the latest draft removed the common existing "reactions" and replaced them with

Return Fire, Counter Attack, Counter Charge and Retreat.

And it is possible to react to every action of the enemy in a specific range (e.g. getting shot at close range allows you to retreat)

How do these mechanics work? Just curious where you found them and how they are executed.

Lanrak wrote:

Do you do realize that an alternating phase game turn based rule set written with a tactical structure , can cover all these 'reactions' as part of the normal game play?

No it cannot.
Not the same way and not with just alternating phases. Of course you can get a tactical structure which would be better than the actual one but it would still be different than IGYG with reactions

I have written and tested several system as an alternative to the current 40k. All of them had their advantages and you can combine different elements of them to get the game working.

To resolve units completely (2 action points for every unit) combined with IGYG or alternating unit activation
keep phases with alternating activation or IGYG
alternating phases
etc

While alternating unit activation combined with completely resolving units (action point system) worked best, it was also the system were players said it is least similar to 40k


My conclusion to all this is that you need to make changes slowly. (if an LRB/Community System should ever get chance)
First make a better 40k which is similar to the existing one and just add small changes which look more like improved exiting rules (advanced reaction rules instead of simple overwatch)

After people accept that it is better to use Community rules as 8th Edition you can change more with a 9th and 10th Edition.


Automatically Appended Next Post:

 EnTyme wrote:

How do these mechanics work? Just curious where you found them and how they are executed.

The basic idea was born soon after GW introduced Overwatch to modern 40k. Because the rules were just the fantasy "stand and shoot" without the advantage of having other options and that already weak melee units got a nerv.
So taking the next logic step was to have retreat as another option for charged units and to add an reaction for melee units (counter charge)

I got than inspired by Starship Troopers and changed the system used there to improve the existing rules in 40k (only single modes react not full units) which solved some problems. After testing we also removed stuff like locked in combat and attacking by Ini because all this would be covered with the new mechanic (eg a unit which want to retreat instead of staying in close combat can do so but will trigger a reaction)

the actual rules are

Units act, Models react

Every time a unit is chosen to do something, the unit is activated and perform an Action.
Every unit can only be selected once per Phase, performing a single Action and has to completely finish it before the next unit is activated. No unit can perform 2 Actions during a Phase nor can the player interrupt an Action of a unit to change the it or activate another unit (eg stop moving a unit because the player realise that it would block another unit and moving the other unit first).
Units and models in Alarm Status can only perform Reactions and no Actions.

If a unit finish an Action all enemy models within 8 inch of a model of that unit can perform a Reaction.
Only affected models can perform a reaction but don’t have to if the player don’t want to react. The target of the reaction can only be the unit which triggered it.


Possible Reactions are:

Return Fire
Reacting models can shoot with -1 to hit at the enemy unit.

Retreat
The reacting models make a single move directly away from the enemy unit.

Counter-Attack
The reacting models can make melee attacks against enemy models in point blank range.

Counter-Charge
The models can make a single move and attack the enemy unit in close combat. This is handled like it would be a normal charge action.


All models use Retreat and Return Fire as standard Reaction. The army list stats which other Reactions can be used or if special Reactions are available.

Not in the same way, no.

Using model reactions in a alternating game turn , is fine for skirmish rules like Infinity and its A.R.O. system.
But I am not sure if using individual model reactions in a game focused on UNIT interaction is a elegant and efficient solution.

It may work , and it may be better than the 'over watch' that GW inflicted on the game.

Using Alternating phases, the reactions you listed could be achieved by...

Return Fire,
Simply achieved by the unit that was fired on in the enemies shooting phase. Firing back at the enemy that fired on them in their shooting phase.
A Shoots at B in As shooting phase., then B shoots at A in the next phase, Bs shooting phase.

Retreat,
Move away from the advancing enemy in your movement phase.
A moves towards B in As movement phase.B moves away from A in Bs movement phase.

Note if assaults only last for one turn.Any unit may attempt to break from assault after one round.

Counter Attack and counter charge
Simply arrived at by unit declaring charges on enemy units after they have charged into assault in their movement phase.

Note..I think it is tactically sound to put ALL movement back into the movement phase.

I am trying to arrive at the most tactical depth from the minimum amount of rules/ complication.
Others may like more complicated rules to arrive at similar game play complexity .