simple use of backdrop on and backdrop off will help to acheive that.
sync on
sync rate 60
backdrop off
for i = 1 to 100
make object cube i,1
position object i,rnd(20)-20,rnd(20)-20,rnd(20)-20
next i
box 0,0,screen width(),screen height(),rgb(0,0,0),rgb(0,0,0),rgb(0,0,250),rgb(0,0,250)
ink rgb(255,255,255),1
center text screen width()/2,screen width()/2,"objects ready press a key"
sync : sync
suspend for key
backdrop on
position camera 0,20,-50
point camera 0,0,0
disable escapekey : while escapekey()=0
sync : endwhile
for i = 1 to 100
delete object i
next i
end