Try something like this: ACLS SPSET 0,0 X=199:Y=119 @LOOP STICK OUT SX,SY IF SY<0 THEN YVEL=-4*SY Y=Y+YVEL:SPOFS 0,X,Y YVEL=YVEL-0.25 IF Y>239 THEN Y=239 VSYNC 1 GOTO @LOOP