Glitch was a browser-based pacifist MMO that ran in some capacity from 2009–2012. The company that made it, Tiny Speck, later converted their in-house chat tool into Slack and rebranded themselves after their new product. I played it during its open beta, starting on September 29, 2011 and ending with the shutdown of the website on December 9, 2012. As part of the site's sunset, the developers released a large archive of the game assets into the public domain.
In the year-and-a-bit that I played, I fell in love with its offbeat worldbuilding, embrace of the weird, and atmospheric art and music. Most of the gameplay in Glitch involved exploring new locations and crafting/gardening mechanics, with occasional fetch quests, social minigames, and platform puzzles. Its natural landscapes were riddled with secret passages and other things to discover, and the players themselves would add other elements to the game world, like setting up newsletters or friendly competitions, or building up interesting structures on their home streets to show off their prowess or design skills. I think if the people playing Animal Crossing: New Horizons now had been exposed to Glitch, a fair number of them might have liked it.
To increase your skills, which would allow you to do more things or make you better at doing them, you would tell your Magic Rock to learn one, which it did in real time whether or not the game was open. The more skills you had, the longer each new skill took, so the order you chose to learn them did have an impact! The timers eventually got long enough at higher levels that they added a skill called "Unlearning," which would allow you to sacrifice a learned skill to get a shorter timer for your next one.
You could write on paper and leave it on the ground or send it to other players as a letter. Letters were obviously useful, but notes dropped on the ground could be used to communicate while offline or away from an area. For instance, asking others not to water a tree so they could finish the quest that asks you to take the last piece of fruit from it. But it wasn't always just functional—the website also archived every note that was left on a public street at the moment the game shut down, which included poetry, reminiscences, and expressions of emotion about the game's ending.
Eggs came from a plant (of dubious biological kingdom) that only grows underground and wheat came from chickens. So in the game world, a fried egg is vegan, but bread isn't. Technically. (Meat came from pigs, who didn't seem bothered by you taking it, and milk came from butterflies.)
At the start, you had to buy houses; I saved up enough for a mud hut in Andra, which is nicer than it sounds. Then they gave every player a home street that they could decorate as they pleased, as well as a butler (a little talking stuffed animal) that could leave messages on your behalf and manage a few other things that I've forgotten.
There are a few groups online working to remake/remix Glitch and its assets, or to archive previous game content. Here are a few of them I've found.