TumeKyouen vs FlipSight

Kyouen (共円) is a geometric concept describing four or more points that all lie on a single circle. "Tsume Kyouen" is a puzzle game where you find the combination of stones that satisfies this condition. Select four stones from those placed on the board and find the "kyouen" — the arrangement where all four lie on a common circle. The rules are straightforward, but as the board grows more complex, spatial reasoning becomes essential. Features - A mathematical puzzle grounded in geometry - Over 10,000 stages with varied challenges - A clean design that keeps the focus on the puzzle - Save and sync your progress with account sign-in Great for fans of mathematics, geometry, or logic-based puzzles.

FlipSight is the app for playing, reviewing and improving at Othello (Reversi). It shares one account with othelloclub.com on the web, so your games and your rating follow you. ■ AI game review A fast, strong engine analyses every move you played. Moves are labelled Book, Brilliant or Blunder so you can see what worked and where it fell apart, and the key moments are called out for you. The evaluation graph shows the exact point the game turned. You can even import a paper scoresheet or a photo of a board and analyse that. ■ Online matches Real-time games against players worldwide, with ratings, rankings and arena events. No opponent around? A range of bots with different strengths and playing styles is always ready, so there is never nothing to play. ■ The largest puzzle collection XOT opening, midgame, early endgame and endgame puzzles, each with its own rating, so you get problems that match your level and watch your puzzle rating move as you solve. Sprint mode counts how many you can solve in one minute, and daily challenges with leaderboards refresh every day. ■ Opening library Named openings animated and evaluated by the AI, with variations you can follow move by move. The app also recognises which opening you played in your own games. ■ Keep and share your games Save the games you play and the ones you analyse, and open them again whenever you like. Share a link or a GIF and your opponent sees exactly the same board. Tournament broadcasts and player records are in here too. ■ New to Othello? The rules take five minutes: trap your opponent's discs between yours to flip them, and whoever has more discs at the end wins. The depth takes rather longer. Learn against the bots, build intuition with puzzles, and let the review tools cut down the mistakes you repeat. Available in 16 languages, including English, Korean, Japanese, Chinese (Simplified and Traditional), Russian and Thai.