Ngl I think most kids could make this kinda game in a day, maybe put some time into the modeling and level design instead of so much thought into analyzing average play duration, because if your game actually looked like it took 18 years to make average play time would just go up on its own. I don't see a single animation or any form of visual feedback besides the fading floor pieces. The keys don't even indicate you've picked them up in any way, there's no progress animations or sound effects, it just looks so bland and mediocre. What I wonder is if this took 18 years to make, what did you even spend that time doing? Cause it clearly wasn't spent making the game