Lightning Grim Anticheat
Lightning Grim Anticheat is an enhanced fork of GrimAC with significant performance improvements, alongside updated systems for reach verification, block placement, and interactive actions within the world. Bugfix requests and enhancement suggestions are welcomed from the community.
As an open-source anti-cheat for Minecraft versions 1.8-1.21.5, it supports players joining via ViaVersion—even those connecting with 1.7 clients. Users connecting through Geyser are exempt from all anti-cheat restrictions.
Unique Features
- WallHit — detects hits through walls
- EntityPierce — monitors hit penetration through entities
- Optimized Bukkit piston event processing
- Improved hitbox and collision calculations
- Packet order verification — resolves slow-movement exploits, auto-block actions, and similar glitches
- Inventory actions monitoring — prevents use of crafting slots as extended inventory and moving while the inventory interface is open
Unlike the original release, the LineOfSightPlace routine—aimed at checks for true block placement visibility and container interactibles line of sight—has not been implemented in this variant.
Building the project
- Clone the repository with
git clone https://github.com/Axionize/LightningGrim - Navigate into LightningGrim using
cd - Execute
gradlew build - Final compiled resources are available under
build/libs
API Access
The built-in Grim compatibility interface enables integration with your plugin infrastructure.
Movement Simulation System
- Analogous simulation to vanilla movement patterns — covering walking, swimming, knockback, cobweb constriction, bubble columns
- Tracks version-specific movement edge cases via robust inner mechanics
- Full player hitbox adaptation that corresponds to any connected client
- Can account for minor precision issues even in obscure scenarios
The entire player interface is simulated in parallel to ensure deterministic detection, almost null false positives, and minimal server impact under load.
Fully Asynchronous and Thread-Safe Infrastructure
Control threads handle motion checks and user events, simplifying uptime optimization and increasing total supported connections per instance.
World State Caching
The system maintains a local replicated world state lookup for every online player, keeping block interfaces consistent across the game,
enabling accurate alignment even after heavy network delay.
Latency Compensation
Server manages all transforms in sync only after definite player confirmation,
eliminating misleading rule activations from lags.
Inventory Compensation
Built-in player inventory correction protocols prevent interactions leading to client-initiated errors.
