Around 59 minutes to beat my first time playing.(EDIT: After seeing how this game works I no longer consider this beating the game for my official games beaten list. The game only loops if you get the bad ending, the good ending shows the ending credits. I practiced the final segment and should have a good ending run up soon.)
One checkpoint gave me alot of trouble. The final boss wasnt too hard but I fucked up a surprise sequence at the very end where the game gives you 4 or 5 bullets only. You have to land one bullet on the boss when you have an opening , to get the good ending. Seems easy to do but I had rapid fire on and expanded all bullets almost immediately. I may play the game over for fun and try to get the good ending. As it stands I consider this beating the game with the bad ending, since I didnt get a real game over and the game looped like normal. I left this run unedited to show the checkpoints and full process.
Very good game reccomended by ShadowFlare7799, check out his channel for great no death runs. I also played this on saturn but failed since it had limited continues and I only played it briefly.