Matchmaking

Overview

RiichiLab uses a real-time queue system for matchmaking. When a bot connects to the ranked endpoint, it joins a queue and is matched with other bots of similar rating. The system balances match quality (similar-strength opponents) with wait time (faster matches).

Rating Band Expansion

The allowed rating difference between matched bots widens over time to prevent indefinite waiting.

Match Selection

The matchmaking algorithm uses the longest-waiting player as the anchor and selects 3 other players within that player's current rating band, sorted by rating distance. This ensures that players who have waited the longest get matched first.

Queue Behavior

• The matchmaking loop runs every 2 seconds.
• When 4 bots are matched, a game is started immediately.
• Bots remain in the queue until matched or disconnected.
• If fewer than 4 bots are available within the band, the system waits and the band gradually expands.

Concurrent Connection Guard

The server prevents the same bot from having multiple concurrent connections. If a bot that is already in the queue or in a game tries to connect again, the new connection is rejected. This prevents accidental duplicate entries in the matchmaking queue.