(Solved by later mono update.)

Title.

Runs fine if I uninstall Mono, but if I have Mono installed on my system, the game just spits errors (mostly "out of memory" stuff) until I uninstall it and reboot. Then, the game works fine again.

Sometimes, the crash happens as soon as the game is starting. Other times, it doesn't crop up until I try to go to the Load Game screen, where it happens while the loading message is at the bottom left corner. Either way, I can't actually make it into gameplay--until I uninstall Mono.

Further, I've tried removing the bundled Mono from the game files. No use. Actually, I've tried a list of things so long I don't care to detail them all. The only thing which works is removing my system Mono.

Unfortunately, I need Mono to run some other programs I use from time to time. Having to remove it every time I want to play and then reinstall it after is not a reasonable solution.

Of note, this only started happening recently. Specifically, it seemed to coincide with running NUPS through Mono. NUPS, of course, ran fine--and still does--but Stardew stopped working immediately after. Possibly a coincidence, though.

I saw a new mono update released, and tried it. Turns out the game works fine after that update.

No idea why system mono would interfere like that, but the game works now. \o/