So it seems that Motion-Twin took down their web games at the beginning of this month. Kind of a sad time, 'cause I definitely spent a lot of time (and a little money) on those. However, considering that those web games were all Flash-based and basically the only way to play them was to download a specialised web browser with a very specific implementation of Flash in it, it's a wonder it was still running for this long.
If you don't know who Motion-Twin is by name, you most likely know at least one of their games. The prequel to Hordes (Die2Nite in English), originally named Hordes Zero, and later renamed Dead Cells. They're a French anarchosyndicalist developer co-op out of Bordeaux who are basically everything I want in a game company. Very right-sized and everyone in the company is equals.
Anyway, while the official games have all been offlined, Motion-Twin open-sourced the majority of their games under CC by-nc-sa 4.0, and even before then, there've been some efforts to get them running independently. Most notably, since the closure, the fan recreation of their biggest (IMO) web game Caverns of Hammerfest (in short terms, a Snow Bros. clone with bombs and long-term progression) was updated to include said long-term progression. (Previously, you'd only get to play the endgame experience as well as user-made levels.) Hopefully, with the official source code made available, more of these will become available in the future.
Also, it's largely because of Motion-Twin that Haxe is a thing today. :3