Addendum: Considering Lance and Mithras' Beyond the Gates of
40k (
https://www.dakkadakka.com/dakkaforum/posts/list/30/733472.page, the "advanced rules" with the
d12 conversion and pin markers are on the 2nd page).
40k used to have two damage mechanics, one for non-vehicle units (do an operation on Strength v. Toughness to determine the target number on a
d6) and one for vehicles (
d6+Strength, damage if it's equal to or greater than the target's armour). 8e
40k has gotten rid of the second and uses only the first, but Antares and Bolt Action got rid of the first and use only the second, and I almost like that better because it's a little easier to explain/keep track of and allows you to make some units invulnerable to some weapons (lasguns v. vehicles, for instance).
I find that Bolt Action/Antares pushes a little to far to small units = better the way they handle pin markers (a unit hit by a weapon that could damage it takes a pin marker, which forces them to make a
Ld test to do anything, penalizes
Ld tests, and destroys the unit if they take too many pins). Lance addresses the issue some in his conversion by requiring an attack to actually remove a wound to do a pin, but I think the issue of spamming Guardsmen to get more chances to put pins on things is still something that requires tweaks to the army lists to address.
The other thing the wild disparity in army sizes does is make gaming the order dice system an issue. For the sake of hyperbole imagine I'm playing a Space Marine army and I have about six units in my 1,000pt list, but my opponent has a Baneblade, ten Guardsmen squads, and two Guard officers. When I have six order dice and he has thirteen the Baneblade gets to fire first every turn, which sort of defeats the purpose of alternating activations, to my mind.
As a concession to units that pay a lot of points to have melee and guns BTGo40k's "Charge" order allows a unit to move, shoot, cast, charge, and fight, which defeats the purpose of trying to make the game faster by letting you do five things per unit per turn, and makes the standard "Advance" order (move, shoot, cast) redundant because it's the same thing but lets you do more stuff.
Let's consider for the moment what you'd to to army lists if you wanted to make
40k more alternating-activations/Antares-rules friendly:
The first issue is melee-only armies and shooting-only armies. Melee-only/shooting-only
units aren't as much of a problem because your army has responses to your opponent engaging in a fashion that unit isn't ready for; if your opponent has some way to rush up and get Tau units in melee you don't have a melee unit to screen with/counter-charge with, but if your opponent runs up and locks a Dark Reaper unit in melee the rest of the army has melee units that can respond effectively.
Right now Daemons and Tau are the only army books that are that one-dimensional; everyone else has tools/options that can do melee and tools/options that can do ranged (even Harlequins and Custodians have gunboats to back up all their melee troops). The short-term solution to Daemons is (unfortunately) soup, either taking multi-god Daemon armies so you can mix in all the Tzeentch stuff that lets you engage at range, or mixing Daemons with
CSM so you have the option to use guns. As for Tau I had a core rulebook rewrite back during 6e based on some ideas from the leaked early playtest 6e rulebook where I defined "melee" as including close-ranged shooting and gave shotguns, carbines, and the like melee profiles to differentiate them from equivalent rifles; that would allow Breachers, carbine Fire Warriors, and maybe Crisis suits to engage in "melee" without throwing out the aesthetic of the Tau by giving them models with swords. Imagine Crisis suits in melee look like the Tau Commander in Dawn of War 1 ducking, dodging, and unleashing short-ranged gun-fu blasts. If pistols were "melee weapons" it'd have the added bonus of making them more relevant since you can actually use them without sacrificing the chance to walk out of melee and shoot the unit with other things the way you do in
40k.
If you were to rejigger the damage mechanic back to something resembling Antares' die+pen v. armour you'd have to address unit type spam. Most of the time you can do that just by restricting people to a Battalion-equivalent
FOC; if the game requires you to take infantry before you can take tanks you'll have infantry and tanks in your army rather than just skipping the infantry and taking the tanks, and requiring/encouraging a reasonable distribution of unit types also requires/encourages a reasonable distribution of weapons rather than spamming just the broken things.
Army-book-wise the only real casualty of requiring people to take infantry is Knights; my opinion on Knights as a Codex rather than individual really big AdMech things that other Imperial armies can borrow is well-documented, so I don't regard it as much of a casualty.
The last problem is trying to constrain people to a narrower range of army sizes so as to prevent the gaming of order dice. At the moment there are squads that cost 4pts/model and squads that cost 100pts/model, and squads might have a minimum anywhere from 3 to 10 models, so I could spend thirty points on one squad (five Dark Eldar Warriors) or a thousand points on one squad (ten Dawneagle jetbikers).
Considering the numbers in Antares the vast majority of basic units are 5-8 models at 17-20pts/model; factor in weapon costs and except for a couple of outliers the cost of adding another minimum Troops squad to your list is between 90 and 130pts. Discarding extreme outliers the cost of adding another minimum Troops squad to a
40k army ranges from 30pts to 110pts for 5-model squads or 40pts to 80pts for 10-model squads.
In
40k a basic rifleman is defined by a nine-number statline and a six-number primary weapon statline, and the difference between two units could be as much as 12 changes there (Guardsman->Intercessor, +1 to
WS,
BS, S, T, W, A,
Ld, +2 to
Sv, +1 weapon range increment, weapon S, weapon
AP) even independent of special rules. In Antares a basic rifleman is defined by a six-number statline and a four-number weapon statline; outside of the Ghar nobody's basic troops deviate from the unit statline by more than two points (Boromites have +1
Str/Co but -1 Ref/
Init so the total is the same), and all of those models' rifles are either the one with 1SV and +10" extreme range or the one with the 2SV mode and the 0SV/2-shot mode.
In practice trying to keep model counts relatively equivalent to current
40k while also trying to constrain the number of individual units you have so as to make Antarean order dice/pin markers work would require essentially the platoon system from 3e-vintage Imperial Guard to return. I'd almost rather consider what
40k models would look like if you tried to port them wholesale over to the Antares statline/resolution mechanics. The statlines are a little less granular (an Antares model has 6 stats rather than
40k's 9, and standard infantry all use the 5/5/5/7/7/8 or deviate by net 0 points (+1 to 2 stats, -1 to 2 stats) while in
40k it's hard to define an average statline at all (the difference between the conscript at the low end and the Intercessor at the high end is 14 net stat points)), but you'd be able to constrain army sizes such that the Bolt Action dice-pulling mechanics might actually work.