Basil the Great Mouse Detective is a platform, action-adventure game designed by Bob Armour and published by Gremlin Graphics in 1987 for the Amstrad CPC, Atari 8-bit computers, and Commodore 64.

The protagonist of the game is a mouse named Basil who resides in the basement of the fabled 221b Baker Street home of Sherlock Holmes.

The player controls Basil by walking around the chambers, passing from one to another through the edges of the screen (if possible) or squeezing through letter slots and other holes in the walls.

The above steps must be repeated until the game is completed, and there are a total of 3 levels: London's shops and docks, the sewers and finally the hideout of the evil Ratigan.

[3] Adam Rigby for The Australian Commodore and Amiga Review said: "Basil the Great Mouse Detective is a good game with a rather refreshing plot".