The Shoot ’em Up Construction Kit is responsible for another interesting release on the Commodore 64 (1941 being the other we are talking about). This one is called Double or Nothing and unique is one good word to describe how it is played. The screen is split down the middle and on either side is an overhead view of a level that you must traverse with your characters. At the same time.
In Double or Nothing you are in control of two characters at the same time. Unlike other games that have tried the split screen gameplay like Cookies and Cream on PS2 or Dashin’ Desperadoes on Sega Genesis, in Double or Nothing you are controlling both characters at the same time- there is no computer, or second player, to help out.
Unique. Yeah, that is the word.
Source: Retro Video Gamer