Support

No. Training and analysis run entirely on-device using the built-in Stockfish engine. An internet connection is only used for showing ads and processing in-app purchases.

Open Settings from the in-game menu. You can adjust thinking time (1–20 seconds per move), hash memory, and the number of CPU threads the engine uses.

Train plays a full game against the engine at your chosen strength. Deep Analysis evaluates every position from both sides at once, showing best-move arrows and centipawn scores so you can study a game or explore variations freely.

In either Train or Deep Analysis, tap the pencil icon to enter Edit Position mode. Drag pieces from the palette onto the board, or drag pieces already on the board to move or remove them. Tap Done when finished — the engine plays or analyzes from your custom position.

Yes. Tap the ← arrow in the toolbar to undo, ← steps back one full move (your move and the engine's reply). Tap → to redo.

Hearts are the in-app currency used to start a game against the engine. You can earn more hearts or purchase a heart pack from the shop. The Engine Unlock and Unlimited Hearts packages permanently remove the heart requirement and unlock the engine's full strength.

Board Capture (setting up a position from a photo of a physical chess board) is marked "Soon" on the home screen — it's planned for a future update and isn't available yet.

Open Settings from the main menu to switch between available languages (English and Vietnamese).

DragonFish-Chess is built on Stockfish, licensed under the GNU GPLv3. In the app, go to Settings → About for links to the license and the public source code of the engine changes we made to run it on iOS.