What do you mean?
You could force to just four direction up down left right
This example was for a 20lines code...take a look.
autocam off:hide mouse:sync on :sync rate 10:ink rgb(255,0,0),0:set text size 30:a=1:av=6
make object box 30000,300,1,230:color object 30000,rgb(0,255,0):set object collision off 30000
make object sphere 40000,6:position object 40000,30,0,30:position camera 0,200,0
point camera 0,0,0:for i= 1 to 6:make object box 50000+i,30,4,4:color object 40000,3000
position object 50000+i,-100+rnd(300),0,-100+rnd(150):yrotate object 50000+i,rnd(3)*90
next i:do:pe=pe+1:make object sphere pe,5.5:position object pe,x,0,z:color object pe,29000
if av=6
if pe>10+uni then delete object pe-9
endif
an=-144+rnd(290):al=-108+rnd(100)
if upkey()then a=1
if downkey()then a=2
if rightkey()then a=3
if leftkey()then a=4
if a=1 then z=z+av
if a=2 then z=z-av
if a=3 then x=x+av
if a=4 then x=x-av
set cursor 20,10:print uni:position object 1,x,0,z:if object collision (40000,0)>0
position object 40000,an,0,al:uni=uni+1:for i= 1 to 6:position object 50000+i,-100+rnd(300),0,-100+rnd(150)
yrotate object 50000+i,rnd(3)*90:next i:endif:for i= 1 to 6:if object collision (50000+i,pe)>0
AV=0:ENDIF:next i :if av=0 then text 120,150,"YOU FAIL !!...":set cursor 300,150:print "Your score ",uni," points"
if object collision(pe,0)>0 then av=0
sync :loop
I'm not a grumpy grandpa