John Phillips‘ Commodore 64 classic, Nebulus, is very good on the Amstrad, although it is quite slow and doesn’t have the intermission challenges of its parent. It doesn’t ruin the game, though. In fact: it may be easier to play than the original due to it being slower.
Pogo‘s quest to make his way to the top of eight cylindrical towers is made super difficult by the presence of enemies and traps that try to constantly knock him into the water below. So the idea is work out how to complete each tower, and do it within a strict time limit. New players may struggle to make headway, but those who are patient enough to learn how to crack the various puzzles will find a brilliant and rewarding game hidden beneath the initial frustration.
Graphically, the Amstrad version isn’t quite as immaculate as the original, but it’s still very good and the controls are responsive and give you what you need to do the job. Nebulus is a great game on the Amstrad, if not quite the classic that the C64 version is.
Note that this game is known as Castelian or Tower Toppler in some regions, but those who know the game call it by its real title: Nebulus. Nebulus was ported by Chris Wood and published in 1988 by Hewson Consultants.
More: Nebulus on Wikipedia