Sentry

Sentry is a freeware remake of Geoff Crammond's all-time classic, The Sentinel. Gameplay remains true to the original, in this battle for dominance via height. Climb higher by building towers of boulders, gain energy by absorbing natural resources and teleport around the strange checkered landscape via robot shells. Meanwhile, you must avoid the deadly gaze of The Sentinel, who looks out from the highest peak. Get higher than him, then absorb him and take his place as ruler.

This Windows version includes texture mapping, dynamic lighting, music, an infinite supply of levels and a host of options. There are even two different stereoscopic modes.