Digital Ranking & ELO Policy

Purpose

This policy governs the digital ranking system used for competitive games at Biciid Center, including Shax and other traditional strategy games. The ranking system ensures:

• Fair skill measurement
• Transparent progression
• Competitive balance
• Protection against manipulation

Rating System Overview

Biciid Center uses an ELO-based rating system adapted for digital play. Each player has:

• A rating score
• A provisional status (for new players)
• A ranking tier

Ratings adjust after each ranked match.

Rating Adjustment Principle

The rating update formula follows:

New Rating = Old Rating + K × (Actual Score − Expected Score)

Where:

• K = development factor
• Actual Score = 1 (win), 0.5 (draw), 0 (loss)
• Expected Score = probability of winning based on rating difference

Expected Score Formula: E = 1 / (1 + 10^((R_opponent − R_player) / 400))

This ensures higher-rated players gain fewer points for expected wins, while lower-rated players gain more for upsets.

K-Factor Policy

• Provisional Players (first 20 games) — Higher K-factor (K=40) for rapid rating calibration
• Established Players — Moderate K-factor (K=32)
• Elite Tier — Lower K-factor (K=16) to stabilize rankings

K-factor may vary based on tournament status, match type, and player activity.

Provisional Period

New players must complete a minimum number of games before:

• Appearing on public leaderboard
• Entering official tournaments

This prevents rating distortion.

Rating Tiers

• Beginner — 0–799
• Intermediate — 800–1199
• Advanced — 1200–1599
• Expert — 1600–1899
• Master — 1900–2199
• Grandmaster — 2200+

Tier thresholds are predefined and publicly available.

Inactivity Policy

Players inactive for extended periods may:

• Experience rating decay
• Be marked inactive
• Require requalification

Decay protects leaderboard relevance.

Rating Protection Mechanisms

To prevent abuse:

• Matches between the same players may have diminishing rating impact
• Collusion detection integrates with ranking system
• Suspicious matches may be nullified

Tournament Rating Policy

Tournament matches may:

• Use adjusted K-factor
• Have higher rating impact
• Include seeding protections

Final tournament standings do not automatically override ELO.

Anti-Manipulation Safeguards

Rating manipulation attempts (e.g., multi-account boosting) result in:

• Rating reset
• Account suspension
• Tournament bans

Transparency & Public Display

Public leaderboards display:

• Rating score
• Tier
• Match history (limited scope)
• Win/Loss record

Statistical integrity is prioritized over vanity metrics.

Review & Adjustment

The rating system may be periodically reviewed to:

• Improve balance
• Address inflation
• Maintain fairness

Changes must be documented and communicated.