The Problem: Lag in Card Games
In most online TCGs, when you draw a card, your device asks a remote server "What card did I get?". The server calculates, then sends the result back. If your internet connection is unstable, the game freezes.
For Covenant Cards, we wanted a "Play Anywhere" experience—planes, subways, bunkers. We needed a system that requires almost zero bandwidth and no constant server handshake.
The Solution: Deterministic Netcode
Instead of sending heavy asset data or card IDs back and forth, our multiplayer engine only exchanges Inputs and a Master Seed.
How it works:
- The Handshake: When Player A and Player B connect, they exchange a single large integer: The Seed.
- The Local Simulation: Both devices initialize their Random Number Generators (RNG) using that identical seed.
- The Prediction: Because the seed is identical, both devices already know what the next 100 cards drawn will be, without needing to ask the network.
- The Gameplay: When Player A draws a card, they simply send the signal "Draw". Player B's device executes the command locally, and because the RNG is synced, it produces the exact same card outcome instantly.
Results
- Zero Latency: The game feels instant because the logic happens locally on your device.
- Offline Tolerance: If the internet cuts out for 5 seconds, the game doesn't disconnect. It just queues the inputs and re-syncs instantly when the data packet gets through.
- Security: To prevent cheating, we use a "Commit-Reveal" cryptographic scheme where players exchange hashes of their future moves before revealing the moves themselves.
This architecture allows Covenant Cards to support Peer-to-Peer play over Bluetooth in "Travel Mode," something practically no other major TCG currently offers.
