"Roll up, roll up, see the amazing Tyrannosaurus Rex, king of the dinosaurs, in his lair." Of all the things you might expect to find running on a ZX81 in 1981, a real time, first-person, 3D maze game would probably be somewhere near "impossible" on your list. Yet, that's exactly what Malcolm Evans was able to pull off--basically in his spare time, as little more than a diversion for himself. Nevertheless, Evans' tinkering became one of the most celebrated games for the ZX81 and a forerunner of the modern first-person game.