Vorticon VI 

    From the little figure in Keen 1 to the Better animated and looking Keen in Keen 6.  Remember when you first saw that little boy running around, shooting, with a helmet on his head?  It was indeed, a pretty poor animation.  But for that time that it was made, it was a hit.  Keen has survived 8 years.  The little figure in Keen 1, lasted throughout Keen 3.  Then you saw the Keen in Keen Dreams.  Better.  But the game pretty much was horrible.  You threw these little bomb things, and could jump.  But no Pogo!  The next keen, which is probably the best, is Keen 4.  The actual character in it lasted through the last of Keen episodes.  Keen 6.  Today, when making 3rd party game, It's pretty hard to make Keen Pogo.  But, it can be done.  As you can hopefully see, Keen has evolved to what we have today, over the progress of 8 years. 

Keen 1-3 
Keen Dreams 

Keen 4-6 
 

~Dopefish Nine