This was a very fun experience! I've been working on some rules for a larger RPG project and wanted to see if they could be boiled down to fit into a one page RPG.
I am a Co-founder Ursatorium Emporium and author of 3d6 Tactics.
1. Overall I think I spent somewhere around 30 hours designing and revising the rules and visuals.
2. Being as concise as possible became the name of the game. Trying to fit an idea into such a small space was a fun exercise and really forced me to think outside the box in terms of design and language.
3. A challenge that I unintentionally imposed on myself was using visual design to inform and dictate mechanical design. The dice icons I created became the basis for the visual "language" of the game and gave rise to the shape of the clocks as well. If I had more time (I joined the jam late,) I would have definitely continued and expanded upon that "language."
4. It may be a shameless plug, but I had a lot of fun helping the author design Mankind: First Dawn. The idea of a prehistoric cooperative rpg is very intriguing and was a lot of fun to see brought to fruition.