Question: What genre is Creatures?
Answer: platform game
platformer
Platform video games

title: Creatures (1990 video game)
text: Creatures is a platform game for the Commodore 64 computer developed by Apex Computer Productions and released in 1990. The game was made by two brothers who were founders of the company, John Rowlands (programming) and Steve Rowlands (music and visual design). It was later ported by WJS Design for Atari ST and released in 1992 and to the Amiga in 1993. 
The backronym "Clyde Radcliffe Exterminates All The Unfriendly