It's appropriate that a game about imposters would have so many imposters. It was inevitable, too. Among Us is popular, and popular games always get ripped off, but on top of that it's got an easily reproducible structure which is forgiving of a little animation and UI jankiness, as those things only make deception trickier, and the strategies more arcane. A knockoff doesn't need the precision design of a platformer like Celeste, for instance. It's also got an instantly identifiable look that's easy to lift wholesale or adapt to a new setting.
So, the rip-offs and tributes came. In China, a game called Werewolf Among Us became a mobile hit. On Steam, numerous Among Us-likes appeared. There's Killer: Infected One of Us, which was briefly called Killer Among Us 3D. There's also Imposter Inside Us, whose title suggests things that I'm not sure were intended. Can't forget Pretend, either, which will be out this January.
Over in VRChat, someone made a 3D Among Us room, and it worked surprisingly well when I tried it. Epic also threw out a limited time mode called Spy Within that, you guessed it, was basically Among Us.
On itch.io, there weren't a bunch of rip-offs, per se, but lots of free tribute games, like Among Us But It's Single Player, which is now called Among Us Story Mode (I like the original name better).
Finally, of course there were Among Us rip-offs on the app stores, too. "With 'Murder us' you will be able to play online with 3-10 players while you fix the spaceship to win," reads the description of one game on the Google Play store, "but be careful and stay alert because among you there are one or two murderers who will not stop until they kill them all!"
If you want to try a game that's similar to Among Us but isn't just trying to capitalize on the current popularity of bean-people (and you're not in a position to play party games like Mafia or Werewolf), I recommend Project Winter. I called it the best bullshitting sim on PC last year, and truth be told, I hadn't even heard of Among Us at that point, because it only became super popular this year. I still stand by that statement, although Project Winter requires more dedication than Among Us—matches are much longer—and it's really best if played with a big group of friends. With strangers, I'm not sure I'd love it.
Among Us is cool too, though: bite-sized, so that you can experience lots of little thrills in quick succession. It's getting a new map soon, and I don't think its developer, InnerSloth, has much to worry about with all the knockoffs. Its players are well trained at spotting imposters.