Marble Madness

Various sources claim that it is not present in the Apple II version. It is. But it is quite obscure. It is reached from the Beginner Race (level 1) and requires two players. I first played this in 1987 and immediately suspected that red and blue colored squares on the unreachable areas were part of the secret. I never managed to reach this unreachable areas. Well, it must require pixel precision to jump to them, in the Apple II version, because I've seen it done in Youtube videos but I'm unable to do so myself. So, jump to the red and blue colored squares on the left unreachable area (both players). Of course, this does not find the secret level. The sharp ramp corner where you jumped to the left unreachable area will be used as a reference. Directly opposite of this corner is a flat corner in the left unreachable area. From this square on this corner count seven up-left squares (the 7th square is horizontally lined to the first sharp ramp corner that can be, possibly, used to jump to the right unreachable area). Then from the 7th square, count three down-left. Place the blue marble here. Place the red marble 3 squares down-right from that one. Now wait.