Windfall Anti-Cheat Banner

Windfall 🇹🇷 Proudly Made in Turkey

Enterprise-grade packet-based anti-cheat for Minecraft 1.7 – 26.2+
_{Fabric · ViaVersion · Geyser}

Build Status Release License Java 17+ Minecraft

Windfall intercepts incoming packets via Fabric Mixins and evaluates player behaviour against a configurable set of checks. A single JAR works across every supported server version — no separate builds required.

55 checks across 4 categories, with a 5-layer compatibility system that adapts detection thresholds per-player based on protocol version, installed mods, and Bedrock status.

Public API available via WindfallAPI for external mods to query player data, violation levels, and check status.

Windfall adapts checks across all supported MC versions and mods through five layers:

┌─────────────────────────────────────────────────────────────┐
│ 1. Version Range minVersion / maxVersion │
│ 2. Mod Detection ViaVersion / Geyser / OCM │
│ 3. Player Profile Protocol / Bedrock / Via gap │
│ 4. Config Override Manual disable per check │
│ 5. Tolerance Multipliers Bedrock + Version gap combined │
└─────────────────────────────────────────────────────────────┘

Checks declare @CheckData(compat = {...}) flags (e.g. VIAVERSION_SENSITIVE, GEYSEIR_SENSITIVE) that control whether the check is disabled or relaxed (higher thresholds) when conditions don't match.

1. Build with Gradle:

./gradlew build

2. Install — place the JAR in mods/:

   • build/libs/windfall-fabric-<version>.jar

3. Optional dependencies (auto-detected):

   • ViaVersion — per-player protocol adaptation
   • ViaBackwards — backward protocol translation
   • Geyser / Floodgate — Bedrock player detection
   • OldCombatMechanics — 1.8 combat emulation

4. Restart the server.

On first run Windfall generates config/windfall-fabric/config.yml. All checks, thresholds, punishment settings, and Discord webhook URLs can be customised there. Use /windfall reload to apply changes without restarting.

windfall/
├── api/ # Public API (WindfallAPI, WindfallProvider, PlayerData)
├── core/
│ ├── check/ # Check registration, base classes, @CheckData
│ │ └── impl/
│ │ ├── combat/ # 12 combat checks
│ │ ├── movement/ # 29 movement checks
│ │ ├── packet/ # 11 packet checks
│ │ └── inventory/ # 1 inventory check
│ ├── physics/ # Prediction engine, physics constants, version branching
│ ├── player/ # WindfallPlayer state, PlayerManager, PlayerProfile, ActionData
│ ├── network/ # PacketListener, Mixin packet interception
│ ├── config/ # WindfallConfig, config.yml parsing
│ ├── punishment/ # PunishmentEngine (warn → kick → ban)
│ ├── severity/ # SeverityManager, VL escalation
│ ├── alert/ # AlertManager, Discord webhook
│ ├── bedrock/ # Geyser detection, BedrockInfo
│ ├── plugin/ # ModDetector (ViaVersion, Geyser, OCM)
│ ├── compensation/ # TransactionManager, PingPongManager, SimulationEngine
│ ├── fingerprint/ # PacketFingerprint, AdaptiveThreshold
│ ├── metrics/ # WindfallPrometheus (Prometheus metrics)
│ └── util/ # MaterialUtils, MathUtil
├── mixin/ # Mixin classes for packet interception
└── WindfallMod.java # Mod entry point

Windfall exposes a public API for external mods:

import io.windfall.anticheat.api.WindfallAPI;
import io.windfall.anticheat.api.WindfallProvider;
import io.windfall.anticheat.api.PlayerData;
// Get API instance
WindfallAPI api = WindfallProvider.getApi();
// Query player data
PlayerData data = api.getPlayerData(player.getUuid());
if (data != null) {
 int vl = data.getViolationLevel("windfall.combat.killaura");
 boolean flagged = data.isFlagged();
}

• PlayerData: Immutable snapshot of player state (VLs, flagged status, check states)
• WindfallAPI: Query player data, check statuses, and plugin information
• Thread-safe: All operations are safe for async access

git clone https://github.com/enis1enis2/WindfallAntiCheatF.git
cd WindfallAntiCheatF
./gradlew build

Requires JDK 17+ and Gradle 9.6+.

Windfall's architecture draws inspiration from several open-source anti-cheat projects. Huge respect to their authors for pioneering these patterns in the community:

• ArrowAntiCheat by StelGR — foundational check framework, @CheckData annotation system, and packet-based detection patterns that Windfall's check registration is built on
• GrimAC by GrimAnticheat — movement prediction engine, physics constants (gravity, drag, friction), and the vertical/horizontal delta validation model used across Windfall's movement checks
• TruthfulAC by TawnyE — per-player state isolation pattern, buffer escalation mechanics, and the decay-based violation level system

If you're building your own anti-cheat, these projects are excellent references for understanding how modern packet-level detection works.

We welcome contributions! Whether it's a bug fix, a new check, or documentation improvement — we'd love your help.

MIT License — Copyright (c) 2026 Enis Polat

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.