Commander Keen 4.5: Parallel World
Commander Keen 4.5: Parallel World is a fangame engine by Andy. (Not to be confused with, Andrew Durdin.) The first engine was presented in May 2010 with a one level demo that doesn't feature the Bean-with-Bacon Megarocket. Keen is seen with recolored clothes. Graphics are ripped from the original Keen games.
When Keen departed the Shadowlands at the end of Keen 4 he is accidentally transported to a parallel world, crashing on a strange planet. In order to escape the parallel world and make his way to the Omegamatic of Keen 5, Commander Keen must find the various parts of his Megarocket that came lose on crashing and repair his ship. This is similar to the plot of Keen 1.