John M. Phillips‘ Commodore 64 classic translates well to the Atari ST.
Nebulus is a rather tough platform game where the aim is to reach the top of an ever more challenging series of cylindrical towers.
You play as “Pogo”, a small, green creature with the ability to jump and fire. Pogo must avoid the many traps and enemies, which will knock him down the tower if they touch him, and use doors and elevators to find the correct path to the top. Pogo only loses a life, though, when he hits the water at the bottom.
Graphically, the Atari ST version is excellent. The rotating towers work nicely and Pogo and all the other sprites are well drawn and animated. If I had one criticism it would be that the colours are a bit garish on some levels, but the ST does have a relatively limited palette.
The gameplay in ST Nebulus is just as hard as the original C64 version, but just as enjoyable and compelling. The first level is fairly straightforward, but after that you’ll find yourself tearing your hair out unless you know exactly what to do. Which comes with practise, like in all good games.
Since the Atari ST conversion of Nebulus was programmed by Phillips himself (he actually did all the graphics and sound himself too) it is about as close to the classic original as anyone could get.
Note: the North American release, by US Gold, was re-named Tower Toppler, which is a banal re-titling if ever there was one.
More: Nebulus on Wikipedia