Knock Down! © 1992 IGT.
3-Coin Multiplier slot.
Model 140B
SS4088
SS3887
SS3675
SS3676
SS3677
SS3834
SS3883
SS3835
COMPUTERS:
Microsoft Windows (2008, "IGT Slots - Little Green Men")
Mac Os X (2008, "IGT Slots - Little Green Men")
IGT Game Index (oct 1997)