CloneKeen is an open-source clone of ID's classic DOS game Commander
Keen. CloneKeen runs under many platforms including Linux & win32. There
are some improvements over the original such as 2-player support. Original
game data files are required.

clonekeen is able to run Commander Keen episodes 1, 2, and 3. Episodes
4 through 6 are not yet supported. Copy the *.ck1, *.ck2, and/or *.ck3
files from the game installation directory to /usr/share/games/clonekeen

Optionally, the package can include the shareware (episode 1) game data
files.