This  was the sample screen for the 3.5 Kb competition coded  by 
Jeff  "Yak  the  Hairy" Minter for us  exclusively!  It  was  not 
entered  in the competition as he had more time than  the  others 
and  he didn't code it at the Convention,  but that  was  already 
agreed with him.
 It's   basically  a  mouse-controlled  version  of  the   VIC-20 
"Gridrunner" without sonics.  But a pretty good game  nonetheless 
(and even less than 3.5 Kb...).