YOUR COLOR. YOUR PACE.
Reversi against the computer. Room to think.
Try an idea, watch the reply and discover how quickly a position can change. You play Black, with no clock rushing your next move.
- You play BlackMake the first move
- Three difficultiesEasy, Medium and Hard
- Separate saveKeep your practice round
Random legal moves for a relaxed introduction.
Searches up to three placements ahead.
Searches up to five placements ahead with a larger budget.
Start your practice round
The button opens computer mode using your saved difficulty, or Medium by default. You control Black and the computer controls White.
Press Vs computer in the game to open Choose difficulty, then select Easy, Medium or Hard. Cancel leaves the mode and level unchanged. Choosing another level keeps the current board and recalculates a pending computer move.
What changes between levels
Easy selects random legal placements. Medium and Hard search possible continuations and score positions using corners, available moves and discs exposed to empty squares. Near the end, disc counts receive more weight.
Medium searches up to three placements and 6,000 positions; Hard searches up to five placements and 24,000 positions. Search may stop at its budget and use the last completed depth. These are practice opponents, with no guarantee of perfect play or a tournament strength rating.
Try a move that leaves fewer replies
Before you place, count the legal choices you might give White. Winning a large number of discs now is not always worth opening a corner later.
Watch the small legal-move rings after each reply. Look for a way to gain a corner, then compare that idea with simply taking the largest capture. A corner stays yours once occupied.
Forced passes and the final count
Start with four discs in the center of an 8 × 8 board. Black goes first. A legal placement traps at least one opposing disc between the new disc and an existing disc of your color. Every trapped line flips, including diagonals. Flips do not cause chain reactions.
A player with no legal move passes automatically. When neither player can move, the round ends, even with empty squares remaining. The larger disc count wins; equal counts are a draw. See the full rules.
Continue the same game later
Your computer game saves separately from Same device play. Reopen computer mode in the same browser to restore the board and selected difficulty, including a pending computer reply.
New round and Play again stay in computer mode. An unfinished round asks before being replaced. To try your plans with another person, choose a shared screen or a private invitation.
GOOD TO KNOW
Reversi Vs Computer FAQ
Can I change difficulty during a game?
Yes. Press Vs computer and choose another level. The current board stays in place.
Why did the computer move twice?
If Black has no legal move, the turn passes automatically. White can then make another placement.
Is Hard unbeatable?
No. It uses a bounded search and can make mistakes.
Can I choose White?
In computer mode you always play Black and start. In Same device mode either person can take either color.