Hmm I've seen this before when a save file gets corrupted or mismatches the update version of the game you're running...sorry about that! There's a guide on our speed running site about how to find your save file, I would navigate to the folder it specifies and try removing your save file and see if restarting the game lets you start a new game. If it still doesn't, there might be a deeper issue I need to investigate. https://www.speedrun.com/lucah/guide/y4no6