We love the fact that you show the duality theme from very start screen, so there's no doubt about how you've applied the theme. We think you did this really well, it's like having a constant hidden wall puzzle from the dungeon crawler classics of old.
Chests are missing faces on the inside of them so you can see the wall through them when they're open.
The inventory screen and overall UI is very clean and well laid out, with an excellent font choice. You've also carried it through to the itch.io page, which we appreciate from a theming perspective. It's great to have a choice of Field of View and even better to have volume sliders. However, you used a different font on the "Flip Lever" text, that's a shame:
The music is very nice and not too intrusive. The sound effects are good too, especially for switching duality.
The pre-rendered combat screen is lovely to look at (thanks mid-journey).
Vertically with stairs was nice, showing it's not just a flat 2D world.
Combat gets interesting when you have to chose how to spend your MP with the combinations of weapons you have and the enemies you have to take down.
Nice graphics on the enemies, UI and environment textures, although it did show that they all came from different asset packs. Even so, you've combined them really well to make it all seem fairly cohesive.
Were we supposed to be able to get outside?
We would actually consider buying and playing this game with a bit more content added to it (and consistent use of fonts!). Well done team!