Time-Gate

Time-Gate (also known as Timegate, 4D Time-Gate or 4D Defender) is an early ZX Spectrum game from Quicksilva, and one of the first 3D combat games.

This video game was (unusually for its time) an original concept, i.e. not a port of an arcade game. The name is derived from its treatment of time as a dimension, in which one could travel (albeit backwards only).