The game's development started around 2005, internally pitched as "Halo" meets "Diablo"". The initial period involved Pitchford selling his team on the idea of the FPS-RPG hybrid, and eventually determining that the FPS genre would be the defining genre for the game. The game's art style was initially more realistic, with visual ideas inspired partially by the "Gears of War" and "Mass Effect" series. The team expanded and prepared for releasing the game's first public reveal in September 2007 via a "Game Informer" cover story, with trailers to be shown in the follow year's E3 and other game conventions, building atop a modified Unreal Engine 3. Elements that were planned at the time of that cover story but that did not make the final game included procedurally generated "loot caves", and the ability to hire non-playable character mercenaries to help in combat. Further, the game initially had three Vault hunters; Brick had not been included yet, as Gearbox thought that it would be interesting in the co-op to have two or more players playing the same characters but with persistent improvements that the players had made to them.