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GrimAC

Stable enough for a small server. Please report any issues. Currently supporting 1.14-1.18 with less tested 1.8-1.13 support.

Test server with bufferless alerts: test.grim.ac

GrimAC is an open source anticheat designed for 1.18 and supporting 1.14-1.18 with half working 1.8-1.13 support. It is free while in beta. It will be sold for $20 on SpigotMC and other various websites, without obfuscation, DRM, subscriptions, or other nonsense that plague other anticheats. Geyser players are fully exempt.

Discord: https://discord.gg/FNRrcGAybJ

Grim supremacy

Here are the main cores that make grim stand out against other anticheats

Movement Simulation Engine

  • We have a 1:1 replication of the player's possible movements
  • This covers everything from basic walking, swimming, knockback, cobwebs, to bubble columns
  • It even covers riding entities from boats to pigs to striders
  • Built upon covering edge cases to confirm accuracy
  • 1.13+ clients on 1.13+ servers, 1.12- clients on 1.13+ servers, 1.13+ clients on 1.12- servers, and 1.12- clients on 1.12- servers are all supported regardless of the large technical changes between these versions.
  • Order of collisions depends on client version and is correct
  • Accounts for minor bounding box differences between versions, for example:
    • Single glass panes will be a + shape for 1.7-1.8 players and * for 1.9+ players
    • 1.13+ clients on 1.8 servers see the + glass pane hitbox due to ViaVersion
    • Many other blocks have this extreme attention to detail.
    • Waterlogged blocks do not exist for 1.12 or below players
    • Blocks that do not exist in the client's version use ViaVersion's replacement block
    • Block data that cannot be translated to previous versions is replaced correctly
    • All vanilla collision boxes have been implemented

Fully asynchronous and multithreaded design

  • All movement checks and the overwhelming majority of listeners are run on the netty thread
  • The anticheat can scale to many hundreds of players, if not more
  • Thread safety is carefully thought out
  • The next core allows for this design

Full world replication

  • The anticheat keeps a replica of the world for each player
  • The replica is created by listening to chunk data packets, block places, and block changes
  • On all versions, chunks are compressed to 16-64 kb per chunk using palettes
  • Using this cache, the anticheat can safety access the world state
  • Per player cache allows for multithreaded design
  • Sending players fake blocks with packets is safe and does not lead to falses
  • The world is recreated for each player to allow lag compensation
  • Client sided blocks cause no issues with packet based blocks. Block glitching does not false the anticheat.

Latency compensation

  • World changes are queue'd until they reach the player
  • This means breaking blocks under a player does not false the anticheat
  • Everything from flying status to movement speed will be latency compensated

Inventory compensation

  • The player's inventory is tracked to prevent ghost blocks at high latency, and other errors

Secure by design, not obscurity

  • All systems are designed to be highly secure and mathematically impossible to bypass
  • For example, the prediction engine knows all possible movements and cannot be bypassed