Sound was fine. It bugged out. Now it's permanently silenced. ;)
I disconnected my laptop from power and HDMI leading to my monitor. So my laptop likely did some driver voodoo and broke the game's sound. At first, it sounded like it was dragging heavily, hiccupping, and then went silent. Rebooting didn't help. Deleting files and unzipping a fresh copy didn't help. Is there a registry entry I need to clear out?