old school game - have you heard of it?

Hey everyone,

I gotta ask because it has been driving me crazy that none of my immediate friends remember this game. Have you ever played Commander Keen 4 (or any in the series)? It is such an old game now and they have it available to play on phone apps now but it is so much harder when it isn't on the computer. Maaaan I remember spending hours playing this game as a kid. hahaha.

It looks like this: