The game will feature relatively in-depth fire-fights with player-formed squads as well as cover and flanking mechanics, within the MMORPG format.[3] However, being true to the setting, war and battles will be a big feature of Warhammer 40,000 Online and Vigil Games are promising to deliver battlegrounds of epic proportions.[4] Controllable vehicles have not been confirmed, but the developers have said that they are aware of how important vehicles are to the setting.[4]
The game will be set in the 41st Millennium, well after the Horus Heresy, and all races important to that period in the setting will be represented, although it has not been revealed which ones will actually be playable.[4] Details about characters are still largely unknown and what's been said so far is only that there will be no non-combat classes in the game, as that would not fit with the background, and that the characters will be highly customizable with things like weapons, books, scrolls and chains hanging from their armour.[4]
Although war and battlefields will be a large part of Warhammer 40,000 Online the scope of the game will include more of the setting than that; Vigil Games’ General Manager David Adams mentions being able to visit "cities (of all scales, types and sizes), exotic alien temples, Chaos shrines, deserted battlefields, mysterious ruins, ancient structures, drifting hulks in space, etc..." and that they will be populated with all manners of non-player characters.[4]
Grouping with other players will not be required to advance through the game although it will be beneficial for tackling both the harder PvE and PvP content of the game.