Commander Keen: Keen Dreams (PC Games)

Introduction
This episode of Commander Keen is often called as "The Lost Episode" or "Keen Episode 3.5", but it's real name is Keen Dreams. This episode doen't belong to a trilogy, like most of the others. This episode is unique and has it's own story. A demo version of this can be downloaded from the downloads section.

The Story
At the dinner table Billy refuses to eat his vegetables and is sent to his room. He falls asleep and wakes up on top of a hill with two spuds wearing helmets and bayonets standing on either side of him. They explain that he was brought here to Tuberia by the Dream Machine and that his master is the evil Boobus Tuber.

Keen's Mission
Now your mission is to safe yourself and get yourself out of Tuberia. In order to do this you need to defeat Boobus Tuber and destroy the Dream Machine. When you start the game, you are presented with a world map like all CK games and you have to enter and complete 13 areas.

More information can be found at: http://www.commander-keen.com/keen-dreams.php

I just love the Commander Keen series =)