I'm not sure why, but I hit a bug here and can't progress. The button sequence was Green - Red - Green, Green - Red, at the start of Stage 4 or 5.
I was really getting into the game, but after failing a few times, I tried to go back and press the green button again. However, the last red button stayed pressed and wouldn't reset, and while the jump effect appeared, the character didn't actually jump.
It’s a bit of a shame, but I still loved the atmosphere and the brutality of the gameplay. It’s totally my style! :D