first platforming puzzle is a bit too glitchy to be playable (jumping from the last platform towards the cog tends to send the player into an inescapable piece of geometry, forcing a full restart)
I took the blank paper before getting and reading the letter from the bird house, and now the map refuses to add Ljusnedal Summer (as the walkthrough says it should do).
input mishandling (primarily in the form of uncommanded double jumps into hazards while carrying items necessitating repeating the whole trek to reacquire said item) renders this game unplayable.
I've tried it just now and discovered that it's impossible to line up for jumping through a one block gap after entering the metroid filled corridors too early.
the first place where the dash is needed is badly designed, when one lands on the edge of the middle platform/island the player is pushed into the second spike-bed instead of being kept on the platform, causing frequent fake deaths.
Bug: orange beam can push the player just below a surface, causing the jump button to stop working. (can be fixed by dashing, but it shouldn't happen in the first place)