RULES OF ENGAGEMENT
The duel
Each duel pairs you against one opponent on the same problem. The fastest correct answer wins. Both wrong? Draw. Both right within a second? Draw.
Opponents
By default we pair you against a stored attempt by a real player at your rating. When no real ghost is available, we drop in a calibrated AI opponent whose accuracy and speed are sampled from a profile matched to your level.
Glicko-2
Your rating starts at 1500 with high uncertainty (RD=350). It moves quickly during your first few duels and stabilizes as the system learns your level. Beat opponents above you and you gain a lot; lose to opponents below you and you drop fast.
Tiers
- IRON < 1200
- BRONZE 1200 – 1399
- SILVER 1400 – 1599
- GOLD 1600 – 1799
- PLATINUM 1800 – 1999
- DIAMOND 2000 – 2199
- MASTER 2200 – 2399
- GRANDMASTER 2400+
Problems
Competition-math style — algebra, number theory, combinatorics, probability, geometry, series. Problems are drafted by Claude Haiku and validated by Claude Sonnet before they go live. Answers are numeric or simple expressions (e.g. 42, 3/4, -1). Whitespace and dollar signs are stripped before comparison.
Identity
You're anonymous. We set one HTTP cookie containing a random UUID — that's your "player." No email, no password, no signup. Clear cookies and you become someone new.
Fair play
Rate-limited per cookie. Look up the answer if you want — you'll just stop climbing. Wins against AI opponents are worth small rating gains; the only way to genuinely climb is to beat real ghosts at your level.