The game centers on a boy called Lee and his faithful dog Ralph. The objective is to control Ralph and guide Lee around six hazardous levels (a City, a Graveyard, A Zoo and a Construction site and a Factory) without waking him up - otherwise you'll lose a life! Lee is sleepwalking hence the name of the game. His task is performed by pushing or kicking Lee around, hanging over holes to prevent him from falling and generally accepting all manner of abuse to keep him alive. Thus, this means you have to run ahead of Lee and check for hazards and traps (and believe me, there are plenty of check for) and neutralizing them. Hazards are everywhere spotted which will fry, burn, electrocute, flatter and zap poor Ralph. There are various power-ups, ranging from whooper cushions to give invisibility and custard pies for bridge building. The game also provides you with a map of each level which you'll need if you plan to get out with your master intact. However at later levels, only a small portion of the map is being displayed, so you'll need to track down a special object to help you reveal the rest of the map. There also a few puzzles to solve during your quest (i.e. trigger certain lifts or avoid boulders) too.
All in all, Sleepwalker is a funny game, with its unique way of gameplay (being ahead of Lee to help him go through various hazards) although it does get repetitive after a while.
The Atari STE version has nice colors and smooth animation using the BLiTTER hardware. Although a few backgrounds from the Amiga OCS and AGA are missing (like the neighborhood buildings), the funny graphics on the STE are as good as the Amiga versions and the use of nice color shadings are pretty much appreciated for me (it looks more impressive than the Amiga version).
The sound is also good featuring a few digitized sound effects but no music while playing. There is a nice intro music theme though followed by a cute intro of the boy being walking at his sleep and the dog trying to save him from the danger!