Transformice is basically a multiplayer-game based in mice and cheese. It was initially developed by Jean Baptiste Le Marchand (Tigrounette in-game) and his friend Mélanie Christin (Melibellule in-game), so... it was an indie-game and still is kind of, but it ended up growing as a small team, Atelier 801. Transformice is kind of based in Tigrounette's experimenting games such as Aaaaah!, Dead Meath and old Fortoresse (these are old games, too).
(Actually it looks like a kid game after many updates, but... :v)
Actually, Transformice originated other games to the Atelier 801 community: Bouboum, Fortoresse (which was a Transformice Lua module) and Neko Dancer. Dead Maze (+/- Celousco) will be ready soon, I guess! There are also forums (which were passed from Flash-base to HTML5 in 2014).
By the term "originated" I mean these games use the same server and are source-based.
Where is it developed? In FlashDevelop or Flash Builder, AFAIK. (Pikashu knows.)
Distribution: SWF and AIR-based installer.
Basically the player goal in-game is generally enter the hole in-map with cheese (you've status, too...), but there are different play modes and even modules, which completely allow players to introduce new modes by themselves in special rooms, otherwise in their tribehouse.
It's a level editor: apparently simple, but allows input XML, allowing hidden functionalities and future editors.
Script Lua, okay.
- & many more.