The game will launch with four main playable races, or factions as they are called in game. These races are the Orks, Space Marines, Chaos Space Marines, and the Eldar. The Tyranid Swarm is also featured, but only as NPCs. Each race will also feature their own unique classes taken from the Warhammer 40,000 universe. The various other races from the universe, such as the Tau and Dark Eldar, will be added "over the game's lifetime", according to the developers.
The game will feature several races for players to choose from. Each race will have its own variety of classes that are unique and recognizable to fans of the Warhammer 40,000 universe. In addition, all factions will have "hero-classes" that are playable but will cost in-game resources to use. The playable races include: Orks, Space Marines, Eldar, and Chaos Space Marines. The Tyranids will be present in game as NPCs, and will act as a balancing force against all factions but mostly concentrate on the race with the most capture land, as well as being the primary enemies in the game's procedurally-created dungeons "Under worlds" and survival "Hives" game modes to provide a Player Versus Environment experience. It is likely that some of the Tyranids will appear as bosses.
Eternal Crusade is limited free-to-play. All players can play for free, but will be limited to playing as Ork Boyz (the basic soldier of the Ork faction) at the game start. Paying players who purchase a copy of the full game will be able to play as all classes from all factions. Also, players will be able to buy specific factions from a game store that will also sell faction appropriate cosmetic items, operating via a microtransaction service.