Combine Strider (Half-Life 2) for People Playground

COMBINE STRIDER

The Strider is a half-synthetic, half-living alien creature that has been used by the Combine as a massive ground force. Three-legged and equipped with a dark matter cannon, it is a formidable opponent for even Gordon Freeman (AKA the Messiah).

No controls (you have to drag it around to move it sadly), and optimized enough to spawn in a few. Don't spawn in 50 though.