A board game play-tracking database like bgstats, but which includes interconnected records (so it’s not just everyone keeping their own database independently) and skill calculations using Trueskill or a similar high-quality system that handles teams and multiplayer better than Elo does.

A document-control system based on something other than Word. Probably latex, markdown, and git.

A hexagon strategy game like homm but a rogue like.

I am from time to time but I clearly do not have enough time.

Also, a commandos like (the Pyro/Eidos one) that takes place during the cold war.