The Dark Mod is a free stealth type standalone video game for Linux, Mac and Windows. It is similar to the popular Thief game but in the Doom 3 engine. In this game you need to control an agile thief to avoid various threats. This game comes with build in level editor using it you can build your own mission levels.
Minimum system requirements: 2GB RAM, 30GB disk space, least a DX9 capable GPU and 512MB VRAM.