This is an old game from 2004, which uses only 97,280 bytes of disk space. However, it is 3D, complete and fully playable. The game use procedural generating techniques to create the most of the game content on the fly, so although the game executable itself is small, it can use a lot of your computer memory when it runs.

Download the game:
https://drive.google.com/file/d/0B5V2PrQ8xX_ETjlqXzYzZVE5bXM/edit?usp=sharing
Links:
http://web.archive.org/web/20110717024227/http://www.theprodukkt.com/kkrieger
http://en.wikipedia.org/wiki/.kkrieger
http://www.pouet.net/prod.php?which=12036

Repost/Via: http://miscool.blogspot.com/2014/04/kkrieger-3d-fps-game-in-just-96-kb.html