Very fun and old school.
My issue is that I tried to pause it by hitting ESC and it took me to the main menu so I was nearly DONE with the game and I tried to find the pause button and I lost all progress....
Good game but next time don't make the bosses recycle.
You really need some checkpoints or an option to continue once you are game over. I didn't get very far but if there really is 50 levels you need some kind of checkpoint system.