Yesterday, I felt ready to give up and skip this year's jam. I was getting deep in a game that borrowed mechanics from like four or five different games, had a bunch of different economies to track and would have needed a ton of paraphernalia in the form of tokens, cards and dice. Finally I realised I wouldn't be able to make that game in that form in the constraints given, and probably it was too complex anyway.
Today, I figured out a different game in which I could probably use some of the art assets I had started working on... So I'll be trying to finish Berlin '70 – Capital of Spies within the deadline, and will add the notes from the original game to my various works in progress. :-)