Cyclevania was our entry for Ludum Dare 41. This was the first time we all got together to jam in person. One of our friends didn't have a laptop so he dragged his massive rig out to my house and we had to set it up on a drafting table I adjusted to sit flat.
The togetherness of the jam really made it my favorite jam experience up to that point. That event also marked the first time I worked with a formally-trained programmer. My self-taught spaghetti code looked monstrous when injected into his clean, well-documented code. I learned a lot about housekeeping in that jam.
I'll go ahead and say the conceit of the game was pretty clever. The theme for Ludum Dare 42 was "Two incompatible genres". We all got mad. It was the only one on the list we didn't want. But we bucked up and rolled with it. We decided to mash-up a cycling game in the style of ExciteBike with the metroidvania genre. This created a unique problem, as the bike only moves in one direction, but metroidvania games rely on exploring branching paths and backtracking.
We came up with the idea of having a series of branching paths the player could navigate, with portals at the end of each to return the player to the start of the level. We had an object that the player needed for the exit on a path that skipped the exit, requiring the play to run the level at least twice. This YouTuber played at the time of the jam.
One of the proudest moments for me in this jam was working out the checkpoint system. I made a series of nodes that would be registered and serialized when the player passed through them. This, way, even when the game was exited, the player could start right back where they left off. File access was something I didn't have to do much before then, as I always found ways around it. College taught me not to fear file processing, then it taught me to fear it for entirely different reasons.