I love the idea that EvE online had, of how soldiers could affect the great war happening in space. 40k is very similar, and to get that “visceral total war” that I think a lot of people would agree to support on any level (be it FPS/TPS, RTS, RPG, ect.) that first off, to even explain how massive the 40k universe is, we have to build it from the ground up.
First, before even describing what kind of game this may be, I fully support the notion of entire worlds being built by players (although major worlds such as Krieg, Macarag, Cadia, ect. Would be under the sole development of the devs.) I imagine it to be a supersized world editor that has an impact on virtually everything you have access to. From the very first outfit, to the possible planet or system you control. On items, they are simply different patterns that can be used, such as attaching a Mars pattern powercell to a Vostroyan lasgun – or crafting your own pattern from a general blueprint of what a Lasgun or Autogun may be. Some weapons would be far more customizable than others, like autoguns compared to boltguns – but no matter what the initial design the stats of the weapon do not change unless you acquire the natural upgrades – as will all customization. When I mean customize everything, I truly mean everything. From what your armor looks like, to tanks, to spacecraft, to cities, to the manufactorums they are designed in, to even the earth you terraform, corrupt, loot, or despoil – everything is uniquely yours. These freedoms are earned by merit and rank just like weapons, titles, and perks in BF3 and CoD but will be described more in depth in section 2.

Meta (the big picture):

Truly unique, the acronym is too long to be effective in describing the grandeur of this masterpiece, for in reality, I’m striving to dream the best possible video game with the best possible setting of all time –and even possibly the best technology we may have in the future (I hope within 10 years).

But really, it’s fairly simple.

We begin by thinking of the setting of the 40k universe in a video game. I imagine it as a cross between the persistent world of Planetfall with the addition of NPC’s fighting alongside players, and the persistent galaxy of EvE online mixed with RTS components that show up at every tier of the game. This we will call the Meta. Keep this in mind.

Just like how players build 40k from the ground up, so too do their characters in a streamlined RPG style. I say streamlined only for the xp mechanics. The game would begin as a sort of RPG where you design your class. Notice this isn’t necessarily your character, but it determines your BF3 type of loadout on the first portion of the game I dub the mirco level where a player’s influence spreads to only to what he can directly see from his character. For example, you want to be a Black Templar SM that favors assault, so you would begin the game as a neophyte with a bolt pistol, combat knife, and the perk “furious charge” to take into your first combat. As you progress in levels, you unlock both gear, and access to other classes you can switch to during lull’s in combat, ie when you die, to address different battlefield situations. In addition, you also unlock the ability to customize more and more of your gear, earn the right to command, gain access to individuals who can drive tanks and pilot aircraft, the authority to captain spacecraft, and even the prestige to claim lordship over an entire world / system – all of which is completely customizable- and for very good reason you will see soon.

As you may have guessed, this game is slightly influenced by EvE online’s venture to RUST. You’re character may either begin in the Army, or the Navy of your faction, of which there are 12 in total, SM, SoB, IG, Mechanicus, CSM, Renegade IG, E, DE, Ork, T, Tau, N. the 12 are divided into 3 factions the IoM, Chaos, and Xenos – IoM is the most cohesive faction, Chaos is less so, and the Xenos faction is by far the most fragmented. This cohesion is a big part in game mechanics as it determines how quickly players advance in rank and gain access to positions of power. From these positions of power, the game begins to change. In an archaic and often cutthroat environment, such as the Xenos faction, advancement is extremely quick compared to the slower advancement of the IoM where in the IG’s case, there are literally billions who must die before you are recognized, and the ever watchful eye of the Inquisition prevents large scale rebellion. Before we cry out that this is a broken system favoring the unity of the IoM over what can be done by simply letting the xenos have vast quantities of NPC’s on the battlefield (which would be the case with the tyrannids anyway) let me explain the key element to the game’s design. With this power, comes the ability to gain vast quantities of resources from the galaxy mostly in the form of NPC’s that can do tasks that a player does not wish to waste time doing, or cannot do effectively by himself. This is done by either earning it honorably by doing duties assigned by your faction, or by stealing it from other players and NPC’s when you slay them – in the same way EvE does. When you die, you lose whatever resources you had on you – but not your rank, titles, or power. This would not affect footsloggers because they either: 1. Have little authority, or 2. Do not carry the resources of an entire planet directly with them. However, those that are the best, most, ruthless, or most tenured at the game will in essence become the End game bosses to defeat in front of their formidable vaults storing the wealth of their star nation - (though many NPC’s would surely exist in the galaxy as well – with their entire worlds pitted against you making any attempt to fight alone against their customizable defenses a futile one. Yet, combat therefore cannot be solely on a FPS or TPS level. It must expand ever outward as players expand in power to prevent low level players from performing heists in the middle of the night when a high level player cannot hope to defend his palace. His armies tirelessly defend it in his stead – his naval forces incinerating probing interlopers as soon as they exit the warp. With these defenses, only a concentrated effort of multiple players could ever hope to make planetfall and begin a campaign with the lord, though even a vastly powerful player may return to the battlefield at any time he so chooses – with any lavish gear he can afford to bring – and may find it vastly entertaining (and perhaps beneficial) to relinquish his forces to an NPC second in command (the same that automatically controls his defenses should he sleep) while he smites his foes with prejudice for daring to step foot upon his home. These points of promotion that allow a player to ascend to officer status, changes the game from the micro level to the macro level. On the macro level, the game changes from a persistent open world RPG FPS/ TPS shooter like Planetside, to DoW2. You are given command of more troops than you may normally have had access to, and as you gain more ground on the planet or space, you are promoted yet again to command entire armies or fleets – which turns the game closer to the original DOW. Eventually, players who are exceptionally good at RTS’s may even try their hand at an epic scale of DOW where battlegroups are deployed and the true scale of war becomes apparent.

Like any game that resembles an RPG, community is an integral part of the experience. In this case, it would be essential for survival to enter into a well organized alliance of players of a certain faction because they could respond to an invasion (NPC or Player) rapidly and effectively. To make this game true to form, the NPC’s need to be made merciless and intelligent, by actually seeking out players that have vast wealth so that other lesser players may slowly build their power without the constant threat of some single player controlled empire barring down upon them. That’s not to say that a massive Orkish NPC Waagh would spare a smaller player on its path to loot the goodies of his opulent neighbor, but the forces directed their by the NPC would be far less than at the more capable commander.

Everything has a purpose. But I am tired, and for some yet unseen purpose, I am forced postpone this section until I have more energy to write it. The jist would be that every level of the game would have some sort of impact to the greater war. So players who do well on a FPS / TPS level would actually directly benefit the next tier of players commanding squads of NPC’s – likely because they are on the same map as the squads of NPC’s spawning in the micro arena’s.