AFK Kicker

How are they made?

Well every second I believe it saves your position and if you don’t move your position for 5 or so minutes then it says you’re afk…?

I’m sure some hacky methods are created with timers and keypresses, etc.

Check the usercmd packages for any pressed keys.
Or for changes, I have a methode that searches for patterns like anti afk bots would use them eg. set key as pressed ever x seconds can be detected.

I used to just do …

+forward
+right

… to bypass AFK checkers when away

I would just check if a pattern in key presses was detected or no key press and after like 3 minutes then require the user to type something into chat within like a minute or it kicks them.

TTT has some pretty decent ways of checking on the client. However you should also perform a few serverside checks (because purely trusting the client is a bad thing).

Avoiding TTT afk detectors is as easy as making you go +left -left +right -right every 15 seconds.