Second attempt
I’ve got it, my new idea to replace the impossible one.
I’m not sure if I should admit this, but it came to me during… an intimate moment. Since my special person is home this weekend I’ve decided to make something the two of us can play together.

Not much to look at yet. When it’s done, I hope to have created a roguey/gauntletty thing in which one player crafts the next dungeon level cavern while the other player hacks their way through the previous one. I’ve just decided to make it top-down rather than a platformer, which might be less of an experience than I originally imagined but it’ll let me get a lot more content done inside the time limit.
I guess I’ll miss out on votes for making something that needs three hands to play, but this is something I’ve wanted to try out for a while. When I was a kid we’d turn anything into an epic role-playing adventure; graph paper, Chinese checkers, Cluedo… I’m not sure if two people can get the same spontaneous story-creating effect with a video game that requires so much less imagination to visualise but I think it’s an interesting idea.