The Sentinel (The Sentry in the U.S.) is one of the first games of the famous designer and coder Geoff Crammond, the author of the Grand Prix series. Developed initially for the BBC Micro, it was released by Firebird in 1986 for Commodore 64, Amstrad CPC, ZX Spectrum, Atari ST, Amiga, and PC.
It's one of the first examples of solid 3D polygon-based graphics running on home computers. Although the speed on 8-bit platforms was not exciting, the game was still amazing and a great example of what could be achieved on platforms like the Commodore 64. Some people define The Sentinel as the first "virtual reality game".
The Sentinel was voted Best Original Game of the Year at the Golden Joystick Awards.
Use the keyboard to play. You can find the instructions here.