Love the idea! I enjoyed how the music would switch between the overworld and the dark world. Art and animations look great as well. I did have some issues with the game however:
- I was unable to open the settings menu. Seems clicking on the button does nothing.
- The walking sound is mostly in my left ear.
- On chrome on windows, CTRL + D is the keyboard shortcut to set a bookmark. I found my game constantly interrupted because I pressed the CTRL key while holding the D key. Having an option to switch key bindings would be nice.
- It was difficult to determine when I could press CTRL to switch realities. I wish there was some sort of UI indicator that would show the cooldown for the switch button. I also feel that the cooldown time should be reduced significantly because I found myself pausing to wait until I was sure I could switch realities.
- Thematically I think the character should only be able to attacking in the underworld since attacking in the overworld does nothing.
While there are some rough edges I think this has the potential to be turned into a fully fledged game. Great work!