Hill And Hole
10 CLOSE#1:OPEN#0,4,"l220":OPEN#1,11,"200"
15 plot range(640,350)
20 xa=6:ya=5:za=11:xb=15:yb=4:zb=-13
30 FOR y=0 TO 10: FOR x =0 TO 20
40 t=x: GOSUB 200: NEXT x: NEXT y
50 FOR x=0 TO 20: FOR y=0 TO 10
60 t=y: GOSUB 200: NEXT y:NEXT x
65 plot pla (22,300),"Grundy Newbrain"
70 END
200 xn=400-x*20+10*y
205 l=SQR((xa-x)^2+(ya-y)^2)+1:l2 = SQR ((xb-x)^2+(yb-y)^2)+1
210 yN =100+y*5-10*(za/l+zb/l2): IF t>0 THEN plot pla(xo,yo),mve(xN,yN)
220 xo=xN:yo=yN
230 RETURN