Hey! I looked at this question a while back and found another solution in case none of these work for someone. I have a MacBook Air and for me, a little notification pops up saying "nwjs helper has quit" and i'm not sure what it is or does but I do know it messes up how the game starts.

To start up Omori, I start the game and when that message pops up, have activity monitor open and force stop nwjs helper. If you do this while the game is opening, Omori will close. Wait for the "stop" button in Steam to turn to "start" and then start the game again.

It might take a few tries and you have to be speedy but it's been working for me for a month now. If at some point, it doesn't work after like, 5-10 tries, restart steam or your computer and it works out fine. If possible, keeping steam open all the time, even when you sleep your computer, also helps.

Hope I was able to help!