[k1ns]

I've built '.io' games of my own and by far the toughest part was the client-server communication, state management, and client-side interpolation. In my experience, the person with the lowest latency has the best experience overall while those with ping >=100 tend to suffer quite a bit more than you'd expect. I'm not well-versed enough in networking to make this statement confidently, so take it with a grain of salt, but I believe the lack of UDP for browser games greatly limits how smooth the experience can be for everyone. It might just be a matter of being enough of an expert to hide the issue though. Hopefully one day I'll figure that out myself!

[user5994461]

It's not a UDP or TCP problem. Some of these games are highly latency sensitive, typically you die if you failed to move within a quarter of a second. They will be unplayable on any mobile or poor wifi connection.