Unblock Slither.io and play, not just load the page

Yes. Loading a game and playing one are different results, and it is worth keeping them apart. A game like this holds a connection open to its server for as long as you are alive in it, and that connection has to carry traffic both ways: what the server tells you about everyone else on the board, and what you send back about where you are steering. Through TrickyBird both directions held. The round ran the way it runs on a direct visit.

No sign-in appears anywhere in that, on either side. Slither.io asks for a nickname and nothing more, and TrickyBird has no account to create, so the whole of it is: open a page, type a name, press Play. If you came looking for a shelf of games rather than one, Poki and CrazyGames open by the same route.

Your browser talks to TrickyBird, and TrickyBird is what talks to Slither.io. It fetches the page and rewrites what is inside, so the links, the images and everything requested later come back to TrickyBird rather than going out to Slither.io, and it leaves a service worker in the tab to catch what loads afterwards. That much is the same for any site.

The live part is the harder half. Most of what a proxy carries is a request that gets answered once and is done with; a game’s connection is opened once and then stays open, with both ends speaking up whenever they have something to say. TrickyBird carries that connection through as well, instead of serving the page and leaving the game to reach its server on its own. Had it done the second thing, the page would have loaded and the round would never have started.

For a long stretch the game did not start through TrickyBird at all: the page came up, you pressed Play, and nothing followed. The repair, when it came, turned out not to be about Slither.io; it was a fault sitting in the way of every game that holds a connection open, so mending it opened the whole class rather than this one title.

Slither.io sees a connection arriving from TrickyBird rather than from your own address, and that holds for the live connection as much as for the page, since both travel the same way. To your network it is a connection to TrickyBird and nothing more; the site you are actually playing is not named anywhere in it.

To run the service and curb abuse, the edge keeps a short access log: a shortened form of your IP address, the hostname of the site you connected to, and basic response details, kept for at most 48 hours, with no TrickyBird account for any of it to attach to.