Great feedback! I also kinda had that feeling as I was designing the level generator. Some ideas I had were:
- Character leveling system for upgrades etc
- Adding more enemies
- Increasing enemy health per floor or set of floors
- Introducing more floor tiles to create other biomes/environments
- I also have been experimenting with adding keys and locked doors, similar to Zelda and Doom.
- Maybe I need to make the boss level a bit earlier as well, maybe at like floor 3-5
I feel like these could help make the player feel as though they are actually progressing.
Let me know if you have any ideas!