I like the Flash game era feel.
So. Initially I played on Firefox, and the spring jump in stage 2 was impossible. Something that is not an issue at all in other browsers (presumably, I played the rest of the game on Edge)
When getting hit, you have no invulnerability frames where you can move. So if you got hit by a slow moving enemy or attack, and if that attack is still in contact with you after your “getting hurt” animation, it doesn’t matter how many powerups you have, you just die.
The music is very loud and there is no way to adjust the volume.
If you game over, you can’t restart the game. Your lives are stuck at 0 so as soon as the opening cutscene finishes you get another gameover. You have to refresh the page to get it to work.
Because powerups are so rare, and getting hit once can instakill you. I ended up beating the game without ever seeing some of the powerups I think.