Today, I burned your latest CD and played the game on my top-loader NGCD + Sony PVM CRT. The game runs quite slow but it is playable and I had fun paying it for a while
I have seen some sprite glitches when an enemy explodes (first level) and when a "bird" enemy is moving (third level).

Is there any kind of cheat available for a level selection or god-mode?

How did you made the "Insert Coin" functionality? I would like to add it to my game too - would you maybe provide the code of it?