1986 · Puzzle · BBC Micro / Multiple
The Sentinel (1986) is Geoff Crammond's 3D puzzle game for the BBC Micro, in which a Synthoid that cannot walk climbs a landscape by absorbing and creating objects, keeping out of the Sentinel's gaze.
The player is a telepathic Synthoid that cannot move. To climb from the lowest ground to the Sentinel's platform it absorbs objects for energy, creates trees, boulders and new Synthoid shells, and transfers its consciousness into a shell higher up. If the Sentinel's gaze falls on the player's square, it drains energy. Every unit the Sentinel absorbs reappears as a tree somewhere on the landscape, so the total energy stays constant. Absorbing the Sentinel ends the level, and the more energy is left, the more levels are skipped.
Geoff Crammond wrote the game for the BBC Micro, and Firebird published it in 1986. Crammond also did the Commodore 64 and Amstrad CPC versions, while Mike Follin converted it to the ZX Spectrum and Steve Bak to the Atari ST and Amiga. In the US it was released as The Sentry.