Hi, thank you for your feedback!
I agree with what you said and I know there were some things that I would like to have implemented but didn't have time to do it properly. I was thinking of making the gates to heaven as the goal and end of the game. Also, the enemies always spawn on the same location, it's a bit predictable but didn't have time to randomise it.
Regarding the ground I tried to make a visual clue to the player that the ground will disappear but couldn't think of anything cool so it ended up like this.
Anyway, thank you for the time you put into playing my game!