I design and run megagames. I've published one, and I hope to publish more in the future.
I also co-run Reading Megagames and Megagame Makers, and if you've played a megagame at UK Games Expo, it was probably my fault.
What are megagames? Megagames are 20-200 player analogue simulations - LARP meets model UN meets social deduction meets strategy board game. They're very versatile as a medium but are usually set in complicated and fast-moving situations where limited information and messy compromises are the order of the day. Hey, if that sounds interesting, here's a website with a calendar of when and where megagames are running.