Megagames
Megagames are best described as RPG/boardgame hybrids that are played by between 30 - 300 people. They are ordinarily team-based and can share some aspects with LARPs, and have been used to recreate everything from historical geopolitical conflicts to fictional wars of conquest on a galactic scale.
The history of megagames begins with the Prussian General Staff's Kriegsspiel in the 19th century, developing via the Royal Military Academy Sandhurst, and finally settling into their current forms as both a fun hobby but also a tool of military, intelligence, and government bodies. You can read more about them at Megagame Assembly or check out the group I help organise, East Midlands Megagames.
I'm currently working on more designs, but have released and run two so far:
Dreams of Empire
Designed as part of a group project, this was my first megagame design effort and focused on a pseudo-historical 1860s that featured airship battles, Lovecraftian monsters, and cut-throat international diplomacy.
Player teams were based around nations (China, France, Austria-Hungary, etc.) along with some "inventor-explorers" who created steampunk inventions whilst the politicians, monarchs and generals negotiated and conquered their way across the world.
Collegium
Partially based on my experience working for a university, Collegium is a university management game that involves balancing budgets, organising research, and keeping the student body happy - all in a world where the supernatural is very real, and the syllabus is sorcerous!
The game parodies real life academia and draws on inspiration from well-loved fantasy tropes blended together to give players some hooks to help drive a fun gameplay experience.