I feel like the theme is not really present, at least i could not find any change of colors. but there are a lot of cool pickups.
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Actually If you press [R], the realm changes (Colors Switch),some enemies hide in the dark and attack you, so the switch mechanic reveal them. It was indeed my mistake to not to introduce this mechanic at the beginning of the game. The jam deadline was reaching close, so in hurry, I added all those perks in the instructions. Take a look at them is U play again. Glad you enjoyed the game!
I did miss that indeed, ok it makes a bit more sense now. A bit my fault not to look at the how to play button but somehow i expected something in the description or when staring the game. So that is the only tip i can give make it more apparent. I updated my rating accordingly. The game feels good for the kind of game it is.