Sky-Jack is an odd platformer game, where at this early stage the player actually glides around, rather than jumps.
I guess the preview was just to test some of the map and sprite mechanics, but little else at this stage. It looks promising enough.
Was anything more done on the game, maybe for a company or just for fun? Being in 1988, it is very possible that this was being done to actually sell.
Do you know anything more about it?