yeah it's not easy, and this is worst-case scenario for networking! I wrote a blog post if you're interested :) https://wayfarer-games.com/blog/one-button-mmo/
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Just read the blog. I love how seriously you've treated this seemingly trivial game. You've thought it all through, done the hard work and the results speak volumes! My attempts at multiplayer have been rather less robust. Perfectly serviceable for the volumes the received, but wouldn't stand up to a serious amount of traffic.