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If this system fails, the game becomes a frustrating, unplayable mess that bleeds players instantly.

Many players believe that matchmaking is intentionally rigged against them, constantly forcing them to fight 'hard counters' after a win streak.
The Elo System Adapted
Most modern strategy games utilize a modified version of the Elo rating system, originally designed for professional chess.

If the system matches you perfectly, you should mathematically have a 50% chance of winning every single game you play.
The algorithm does not care what deck you are playing.With millions of players, you will occasionally draw a bad matchup.In the lower arenas, the system often includes 'bots'. The Problem of Card Levels
The standard Elo system works perfectly for chess because all pieces are equal, but tower rush games feature upgradeable cards.

The system will try its best to match you with someone who has the same trophies AND a similar tower level.
Conspiracy TheoryThe Mathematical RealityForced Loss StreaksThe algorithm does not force losses; you are simply playing tilted against harder opponents because your MMR is inflatedAnti-Strategy CodeDevelopers have confirmed repeatedly that the algorithm does not read the contents of your deck when finding an opponent Maintaining Competitive Integrity
By artificially capping all card levels to a specific number, the algorithm can rely purely on the Elo rating.

When levels are equalized, the matchmaking system shines, ensuring that the better player almost always wins.