Retro Software's The Krystal Connection is a fairly standard platform game where each screen is accessed serially, and might just as easily have been released in 1984. Apparently, this is when it was actually written.
Your aim is to collect up all the bones lying around. Each screen also features a few patrolling nasties which detect your presence and come hurtling toward you as soon as you both share a platform. They have to be either avoided, or temporarily trapped, allowing you to pass "through" them. Hence you must leave yourself enough time when moving onto a platform to: drop a trap, take a step backwards, wait for the trap to capture the bad guy and then run past him. You access each platform via a lift which you can direct up and down when standing on it.
As a game concept, this is quite a fiddly affair. Krystal Connection's execution of it is also wildly unpredictable. Dropping the trap seems sluggish; often the "drop" key just doesn't register. Yet when attempting to take a step backwards, the direction keys can register twice. Both tedious features of the game render it pretty unenjoyable, and the level design also feels unimaginative.
A cassette-based copy of The Krystal Connection costs £2.95 plus P&P. Curiously, Retro Software also has free releases (amongst them Castle Raider, Jungle Journey and Hard Hat Harry 1 & 2) which are, on any view, superior to this one.