The gameplay is clear, but it is really frustrating.
I really wish there was some feedback when I become invisible. Did I land on something? Maybe like a dust effect when a character lands would be decent.
The punishment for the player for not guessing whether they landed or not is too harsh. And even the invisiblity is really hard to guess. Maybe something along the lines of a display of how much before invisibilty kicks in would help.
The "You Died" flavor text was not helping at all, in fact, was really irritating.
The graphics can really use some upgrade. The idea of collecting a key and going back is not creative to be honest, but the concept of going invisible would have been cool if it was implemented better.
I hope this jam helped you learn something
Good luck.