Makes good use of the limitation, and clever enough that I made it all the way to the end. I particularly enjoyed the darkness mechanic, though I do wish it wasn't required to benefit from the fire-walk (that is, the Fire-walking ability doesn't open any rooms that don't also have darkness, essentially requiring 2 upgrades to access them meaningfully). Also, The UI gets in the way of the darksight reveal circle, stunting its utility.
Expanding on what others have said, swapping from "i" to mouse is pretty awkward. The spacebar would have been the ideal candidate for this use-case, but making all the collectables buttons to be interacted with via the mouse would have also been more comfortable.
Otherwise, an enjoyable and relaxing little adventure. Good luck in the jam :D