10 X%=SCREENHEIGHT(0)/2
20 GELLOAD "1","1.PNG" : GELLOAD "2","2.PNG"
30 FOR I%=1 TO SCREENHEIGHT(0)
40 SPRITEGEL "GEL","1"
50 IF MOD (I%,2)=0 THEN SPRITEGEL "GEL","2"
60 SPRITEMOVE "GEL", X%, I%
75 SLEEP 15
80 NEXT I%
90 END