Anti-Cheat Measures in MTG Commander Game Engine

This document outlines the anti-cheat mechanisms implemented in the MTG Commander game engine to ensure fair gameplay in multiplayer sessions.

Overview

Preventing cheating is essential for maintaining a fair and enjoyable multiplayer experience. The MTG Commander game engine implements several layers of anti-cheat measures to detect and prevent various forms of cheating.

Types of Cheating Addressed

Client Modification: Tampering with the game client to gain advantages
Memory Manipulation: Directly modifying game memory to alter game state
Network Manipulation: Intercepting and modifying network traffic
Information Exposure: Accessing hidden information (opponent's hands, library order)
Automation/Botting: Using automated tools to play the game

Implementation Approach

Server Authority Model

The game uses a server-authoritative model where critical game state and rules enforcement happens on the server:

#![allow(unused)]
fn main() {
// Server-side validation of player actions
fn validate_play_card_action(
    mut commands: Commands,
    mut server: ResMut<RepliconServer>,
    mut play_events: EventReader<PlayCardEvent>,
    game_states: Query<&GameState>,
    players: Query<(Entity, &Player, &Hand)>,
) {
    for event in play_events.read() {
        let client_id = event.client_id;
        let card_id = event.card_id;
        
        // Find the player entity for this client
        if let Some((player_entity, player, hand)) = players
            .iter()
            .find(|(_, player, _)| player.client_id == client_id) 
        {
            // Verify the player actually has this card in hand
            if !hand.cards.contains(&card_id) {
                // Log potential cheating attempt
                warn!("Potential cheat detected: Client {} attempted to play card {} not in hand", client_id, card_id);
                
                // Send cheat detection notification
                server.send_message(client_id, CheatWarning { 
                    reason: "Attempted to play card not in hand".to_string() 
                });
                
                // Skip processing this invalid action
                continue;
            }
            
            // Continue with normal processing if validation passes
            // ...
        }
    }
}
}

Client-Side Integrity Checks

The client includes integrity verification to detect tampering:

#![allow(unused)]
fn main() {
// Client-side integrity check system
fn verify_client_integrity(
    mut integrity_state: ResMut<IntegrityState>,
    mut client: ResMut<RepliconClient>,
) {
    // Perform integrity checks
    let checksum = calculate_code_checksum();
    
    // If checksum doesn't match expected value
    if checksum != integrity_state.expected_checksum {
        // Report integrity failure to server
        client.send_message(IntegrityFailure {
            reason: "Client code integrity check failed".to_string(),
            details: format!("Expected: {}, Got: {}", 
                integrity_state.expected_checksum, checksum),
        });
        
        // Set integrity failure state
        integrity_state.integrity_failed = true;
    }
}
}

Network Traffic Validation

All network traffic is validated for consistency and authenticity:

#![allow(unused)]
fn main() {
// Server-side network traffic validation
fn validate_network_messages(
    mut server: ResMut<RepliconServer>,
    mut message_events: EventReader<NetworkMessageEvent>,
    client_states: Query<&ClientState>,
) {
    for event in message_events.read() {
        // Verify message sequence is correct (no missing messages)
        if let Ok(client_state) = client_states.get(event.client_entity) {
            if event.sequence_number != client_state.next_expected_sequence {
                // Potential replay or injection attack
                warn!("Sequence mismatch for client {}: Expected {}, got {}", 
                    event.client_id, client_state.next_expected_sequence, event.sequence_number);
                
                // Take appropriate action (request resync, disconnect, etc.)
                // ...
            }
        }
        
        // Verify message signature if using signed messages
        if !verify_message_signature(&event.message, &event.signature) {
            // Message tampering detected
            warn!("Invalid message signature from client {}", event.client_id);
            
            // Take appropriate action
            // ...
        }
    }
}
}

Detection and Response

Anomaly Detection

The system monitors for statistical anomalies and suspicious patterns:

Unusual timing between actions
Statistically improbable sequences of draws or plays
Impossible knowledge of hidden information

Response to Detected Cheating

When potential cheating is detected, the system can respond in several ways:

Warning: For minor or first offenses
Game Termination: Ending the current game
Temporary Ban: Restricting access for a period
Permanent Ban: Blocking the user entirely
Silent Monitoring: Continuing to monitor without immediate action

Testing Anti-Cheat Measures

Testing the anti-cheat system involves:

Simulated Attacks: Attempting various cheating methods in a controlled environment
Penetration Testing: Having security experts attempt to bypass protections
False Positive Analysis: Ensuring legitimate players aren't falsely flagged

For detailed testing procedures, see the Security Testing Strategy.

Future Enhancements

Planned improvements to the anti-cheat system include:

Machine learning-based anomaly detection
Enhanced client-side protection against memory editing
Improved server-side validation of complex game states
Community reporting and review system

This documentation will be updated as anti-cheat measures evolve.

Rummage Documentation