Anti-Cheat are plugins added to Minecraft servers to prevent players from cheating with hacked clients. When it comes to 2b2t and several other anarchy servers, anti-cheats have been enabled, however, usually to prevent extreme forms of cheating (flying, super speed, etc.) in order to provide fair gameplay on the server, while fewer OP forms are usually accepted (Jesus, Kill Aura, etc.).
This page will explain the various forms of anti-cheats used on 2b2t, their discrepancies, and criticism.
NoCheatPlus (or "NCP") is the oldest anti-cheat to date and has been used by Hause since the rise of server networks, plugins, and hacked clients way back around 2012. NCP can be used on Bukkit-based servers, such as Spigot or Paper, which is currently deployed on 2b.
The anti-cheat gained a lot of criticism by early players as they could no longer fly around or go at insane speeds. People bashed Hause because of this and criticized that the anti-cheat prevented true anarchy. Despite critics, Hause never removed the anti-cheat and it has been a part of the server until getting replaced by AAC.
The anti-cheat, over time, became somewhat praised by the community due to the fact that it prevents game breaking hacks but yet, for the most part, allows normal cheats like Kill Aura and things of that nature, allowing for some of the true anarchy to remain on the server.
Advanced Anti Cheat ("AAC") is another anti-cheat added to 2b2t by either Hause or Curtis. AAC was introduced sometime in April 25th, 2017 and removed around Late April/Early May. It is only available on Spigot and Paper.
This anti-cheat was heavily criticized as players, like torogadude, have noted that it prevented many normal hacks, unlike NCP which to a degree did not. Things like Speed Mining, Kill Aura, Jesus, and modest speedhacks were known to kick players from the server.
AAC had been rendering many of the most popular cheat clients on the server, such as Impact, Future, and Wurst, almost useless. Players had to be conscient about how much they make use of their regular hacks. In fact, even players without hacks were kicked due to horrendous lag. Hause was sent hundreds of emails on the day it was added in order for it to be removed. According to reports, 90 players, including no hack players, were kicked on the first day.
Switching between anti-cheats
Revert to NCP (AAC's Fail)
Eventually, due to critiscism and issues Hause finally listened and reverted the anti-cheat back to NCP. This was most likely due to an update in NCP and that the Apocalypse Exploit has been patched due to an IRC plugin that was implemented in order to fix the source code and tracks issues.(which exploit and plugin?)
Reverting back to AAC
In early April of 2018 2b2t went back to AAC for unknown reasons. It had been on the server for a few months, causing various issues to players and thus the many complaints about it. Eventually it was replaced once again by NCP.
AAC during 7th Incursion
When it had become widely known of FuzeIII joining the server and players gathering to form the 7th Incursion, Hause brought back AAC for the duration of the incursion, limiting many in use of their cheats. As before, many players were upset and demanded to revert this change, to no avail. Finally on November 19th 2018, once player numbers completely settled down and 7th Incursion had come to an end, AAC was reverted to NCP. Another minor reason might have been problems with slow chunk generation.