Also the name of
game on the
Commodore 64, by
Geoff Crammond.
A stunningly original game, the basic premise was the player (in a robot body) escaping from a three Dimensional landscape, which was watched over by the sentinel.
The originality stemmed from the fact that you couldn't actually just move around, the only way to move was to teleport. You could only teleport to another robot body (which you first create), on the square that you wanted to move to.
Creating a new robot costs energy, energy is obtained by absorbing old robot bodies you no longer need, and absorbing the trees dotted around the landscape.
It was also possible to create boulders, that could be stacked. Stacking several boulders, then creating a robot body on top was the way to gain a higher point in the landscape.
However, all teleporting, creating and absorbing can only be performed on objects in squares that you can see the base of. This is the key to the whole game, and why it is so challenging.
To make matters more difficult, there is the Sentinel. He watches over the entire landscape, slowly rotating to peruse all areas. If he saw you, he would start draining your energy very quickly. You needed to absorb the sentinel to complete the level, teleporting to the next was only possible from the sentinels platform.
The amount of energy you had left at the end of the level, would determine how many levels you skipped.
Truly a classic game, and a prime candidate for an open source reworking.