Commander Keen 4 Ultimate player get stuck in the map when going to the Isle of Tar
I cannot be sure if the problem is in the Commander Genius or Keen4U side. But here it is: start the game, beat the Border Village, and beat Miraga.
Done so, go on the Isle of Tar but instead of starting the level try to go in the Isle of Fire instead. To swim back will be impossible and Keen will be stuck in the top right part of the lake.