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MMR & Ranking System

G-RANK uses a custom MMR (Matchmaking Rating) system — not Elo. Each tier has different gain and loss rates designed to incentivize continued play at higher tiers while making progression feel meaningful.

Rank Tiers​

TierMMR RangeWin GainLoss Deduction
Bronze0 – 499+50-25
Silver500 – 999+40-20
Gold1000 – 1499+32-18
Platinum1500 – 1999+30-20
Diamond2000 – 2499+25-25
Master2500 – 2999+20-25
Elite3000++15-30

Tier Design Rationale​

TierPhilosophy
Bronze/SilverHigh win gains (+50/+40) to encourage new players and reward early progress
Gold/PlatinumModerate gains; the system starts to demand consistency
DiamondSymmetric gain/loss (+25/-25) — the inflection point
MasterGains fall below losses (-25 > +20) — must win more than lose to climb
EliteHardest to climb (+15/-30) — position is actively contested

This design means higher-tier players must maintain a positive win rate to stay in their tier, preventing rating inflation at the top.

MMR Calculation​

MMR is adjusted after each validated match result:

function calculateNewMmr(currentMmr, won) {
  const tier = getTierFromMmr(currentMmr);

  if (won) {
    return Math.max(0, currentMmr + tier.winGain);
  } else {
    return Math.max(0, currentMmr - tier.lossPenalty);
  }
}

function getTierFromMmr(mmr) {
  if (mmr >= 3000) return { name: 'Elite',    winGain: 15, lossPenalty: 30 };
  if (mmr >= 2500) return { name: 'Master',   winGain: 20, lossPenalty: 25 };
  if (mmr >= 2000) return { name: 'Diamond',  winGain: 25, lossPenalty: 25 };
  if (mmr >= 1500) return { name: 'Platinum', winGain: 30, lossPenalty: 20 };
  if (mmr >= 1000) return { name: 'Gold',     winGain: 32, lossPenalty: 18 };
  if (mmr >= 500)  return { name: 'Silver',   winGain: 40, lossPenalty: 20 };
  return              { name: 'Bronze',   winGain: 50, lossPenalty: 25 };
}

Key rules:

  • MMR floor is 0 — cannot go negative.
  • Tier is calculated from the player's MMR at the time of the match result, not the current tier.
  • MMR updates are triggered when a match result is submitted and validated.

Match Result Submission​

Match results are submitted via POST /api/match-results/submit-replay. The flow is:

1. Player submits: { lobbyId, replayUrl, winnerId }

2. Server validates:
   a. lobbyId exists and is in 'completed' status (or transitions it)
   b. replayUrl matches the game's accepted pattern
   c. winnerId is a valid participant of the lobby

3. Server records match result in matchresults collection

4. Server updates MMR:
   - Winner: currentMmr + tier.winGain
   - Loser(s): currentMmr - tier.lossPenalty (capped at 0)

5. Win/loss counters on User document are incremented

Leaderboard​

The leaderboard is served from GET /api/leaderboard and returns users sorted by mmr descending.

{
  "players": [
    {
      "rank": 1,
      "username": "ElitePlayer",
      "mmr": 4200,
      "tier": "Elite",
      "wins": 180,
      "losses": 40
    },
    {
      "rank": 2,
      "username": "MasterGrind",
      "mmr": 2890,
      "tier": "Master",
      "wins": 120,
      "losses": 60
    }
  ],
  "total": 1500,
  "page": 1,
  "pages": 75
}

MMR Display on Dashboard​

The Dashboard page shows:

  • Current MMR value
  • Current tier name and badge
  • Progress bar from current tier floor to next tier threshold
  • Win/loss record
Example for a Gold player at 1250 MMR:
  Gold threshold:     1000
  Platinum threshold: 1500
  Progress:           (1250 - 1000) / (1500 - 1000) = 50%

Future Considerations​

  • Season resets: Planned seasonal MMR soft resets (e.g., compress all MMR toward the tier midpoint).
  • Placement matches: Initial unranked placement matches to seed new players above Bronze.
  • Per-game MMR: Separate MMR per game (LoL MMR vs Showdown MMR) is a potential future feature.