What a blast! This was my first jam, and I was really happy to have a full ten days, because trying to finish in 3 would have been rough on my health.
Worst moment: getting all the coding complete and realizing I have no idea what I'm going to do for level design. By that point I was down to two days left, but I knew I had been heads-down in the game so long that I could no longer be relied upon to determine what is or isn't fun.
Best moment: I spent most of the jam on a business trip (had a lot of solo nights at the hotel for hack time which worked out really well) but once I got back home and got to show my game to my kids, they were able to playtest, spot bugs, and even help with level design a fair bit. Using Tiled for the levels made it really easy for them to pitch in. Their enthusiasm helped push me over the line to finish (just barely) in time.