Strife

STRIFE is a computer game that was an big leap forward from the standard DOOM engine. Strife pushed the engine to it's limits and allowed players to talk to other characters in the game's world.

There were computer controlled allies that would fight alongside the primary character. The world was a comprehensive world, not divided into levels like other 3D shooters of the time. The environment was interconnected much in the same way as Half-Life.

Unfortunately, even though the game brought many improvements to the Doom engine, it took too long to come out and could not compete graphically with other games that were being released at that time, including id Software's Quake.