[1.5.5] Game in broken state after getting stuck

[LordErnie]

Game version: 1.5.5 Steam
OS: Windows

I was doing a Normal run with a Stone Warden, when I encountered what I think was a radiant horror, among several other enemies. Upon encountering them, the radiant horror used its sigil attack, which made the game choke for a few moments, then instead of the usual graphic, I got a semi-transparent overlay, most of the graphics were very blurry, and the game didn't respond to any commands.

I used Windows Task Manager to shut down the game, and restarted. When I loaded my savegame, my character was back in a very different situation (purchasing a randart). When I went back east, however, I noticed my map had reset to the starting situation of arriving in the East. Even though I had already cleared 3/4 Orc camps, the only visible locations on the map are Gates of Morning and the Unremarkable Cave. Dialog is still in sync with my quests, though, so I can't use dialog to retrigger things.

I sadly don't have the game logs from just after the bug, as I restarted the game. I can upload any character files that would be meaningful, though.