AstroMan Dungeon

I think that your modifications are headed in the right direction! The best advice that I can give you in terms of level design would be to make sure that each level has some sort of unique identifier. New types of challenges, enemies, obstacles, or powerups can massively help with this. Putting some time into playtesting and differentiating your levels (to figure out, from a player's perspective, how the level plays) can also give you some direction in how to design things.

I like your idea of adding powerups - I'm curious to see what types of abilities and modifiers you'll give the player to change up gameplay. I also like your idea of adding a boss. Good luck!