Well crap. I got the "Failed to create save data. Exit the game and delete save data." issue.
Which is lovely for various reasons. There's no UI at all and it's still that dumb unmoveable faux-fullscreen, so you can't even alt-tab out or reach the task manager (you can, but you can't see anything). Fortunately alt-F4 works.
It doesn't tell you where the saves are located. Turns out they aren't in My Documents, or Steam's "common" folder, but in the userdata folder under the helpful "287700". And maybe 311340??
(The reason is that they're stored on the Steam Cloud, but still. Very unhelpful.)
And when I did delete the saves and launched, Steam just quietly redownloaded them... And they're still broken, so it gave me the exact same unhelpful error!
It's possible that this is partially my fault, since I accidentally left OBS recording (only audio though, by accident) which filled up my hard drive. Same thing happened to me in Borderlands: tPS, and I lost progress from the point my hard drive filled. It silently failed to update the cloud saves at that point. Which sucked... but, at least it didn't silently *overwrite my cloud save with a corrupted one*!
I'm not that upset about having to replay the actual missions, but I'm not excited about redoing the whole prologue.
Fakedit: Fuck's sake, it won't let me do a "first launch" with Steam in offline mode. So how am I supposed to meaningfully clear my save data!?
Okay, phew, Steam does have an option to disable syncing with the cloud for a specific game.
... But it's still downloading the bad save data!?!
I finally had to follow every step in this thread from 2012 to trick steam into deleting the corrupt files:
http://forums.steampowered.com/forums/showthread.php?t=2470784This wouldn't be quite so bad except that apparently many other people have experienced save corruption as well, with this game. Scary thought. Blugh.
Oh. It let me choose my brightness, and then it tried to autosave and failed again. "Exit the game and delete save data."
...I'll throw together the politest support ticket I can.