Every move, judged on our servers.
Real-time chess and checkers in the browser. The server checks each move against the whole game, runs both clocks and keeps the record.
- ply 24Rd8legalblack 4:35.4 → white
- ply 25Rxd7legalwhite 4:44.2 → black
- ply 26Rxd7legalblack 4:34.9 → white
- ply 27Rd1legalwhite 4:36.6 → black
- ply 28Qe6legalblack 4:24.7 → white
- ply 29Bxd7+legalwhite 4:38.0 → black
- ply 30Nxd7legalblack 4:27.1 → white
- ply 31Qb8+legalwhite 4:38.6 → black
- ply 32Nxb8legalblack 4:26.8 → white
- ply 33Rd8#legalwhite 4:40.6 · checkmate, 1–0
ReplayA dashed border means sample or replayed data, computed by Ocheso's own code; the line underneath says how it was made. Real, live data sits in a solid frame. Paris, 1858 · every move checked by Ocheso's referee
1 · The referee
Four checks, every move.
Sent.
The move reaches Ocheso as UCI for chess (
e2e4) or a numbered path for checkers (32-28,28x19x10).Rebuilt.
The referee rebuilds the position from the game's whole record, not from what the browser says the position is.
Checked.
Is it legal? Is it this player's turn? Is there time on their clock?
Recorded.
The move is stored, the clocks are charged on server time, and both players and any spectators see it.
2 · Rules
Two games, by the book.
Chess
Standard rules. A game ends by checkmate, stalemate, insufficient material, repetition or the fifty-move rule, and the last two end it at once: online, nobody should have to know to claim.
Checkers
International (10×10) and Brazilian (8×8) under FMJD rules: captures are compulsory and you must take the most pieces; men capture backwards; kings fly; captured pieces stay on the board, blocking, until the move ends, and none can be jumped twice; a man is crowned only if it ends its move on the far row; threefold repetition is a draw, and so are 25 moves each with only kings and no capture.
Captures on the board
- 26x19x12x3x10takes 4The only legal move
- 27x18takes 1Refused: a longer capture is on the board
All 4 come off together. The man passed through 3 on the far row and ends on 10, so it isn't crowned.
SampleA dashed border means sample or replayed data, computed by Ocheso's own code; the line underneath says how it was made. Real, live data sits in a solid frame. Position checked by Ocheso's referee
3 · Clocks
A clock nobody can talk into more time.
Your screen shows the clock; our server keeps it. Increments are added on the server. A slow connection can't buy time, and closing the tab doesn't stop the clock. When time runs out, the opponent can claim the game, and if the player with time left could never have mated, it's a draw.
- 0.0 sserverWhite's clock is running on the server
- 2.4 sscreenyou play g1f3 with 5.6 on your screen; it's sent
- 4.0 sserverg1f3 arrives: 4.0 s charged (2.4 s thinking, 1.6 s on the way), +3 s
- 5.6 sscreenyour screen catches up: 7.0 left
SampleA dashed border means sample or replayed data, computed by Ocheso's own code; the line underneath says how it was made. Real, live data sits in a solid frame. A simulated connection · the rule is the server's own: a move is charged until it arrives
4 · During a game
At the board.
Offer a draw, accept or decline one, or resign. Organisers decide whether games can be watched, and live games are listed on the tournament page.
5 · Ratings
Ratings, plainly.
Ocheso uses Elo. K is 32 below 2100, 24 below 2400 and 16 above. A game is rated only when both players moved and the board decided the result: a no-show or a first-move resignation isn't rated, and correcting a result doesn't re-rate it. Events that organisations run through Ocheso for Platforms, in early access, are unrated unless the organiser chooses otherwise.
| Side | Before | K | Expected score | After | Change |
|---|---|---|---|---|---|
| White | 1640 | 32 | 0.262 | 1664 | +24 |
| Black | 1820 | 32 | 0.738 | 1796 | −24 |
ew = 1 / (1 + 10(1820 − 1640) / 400) = 0.262Δ = round(K × (score − expected))
Same formula as the database: expected score, each side's K from its own rating, rounded half away from zero
Known limits
- Ocheso judges legality and time. It doesn't screen games for engine assistance today.
- No PGN download yet.