Quick Start

A simple rule is all you need to start: each connected group must contain exactly as many matching numbered tiles as its number. Three touching 3s make a complete cluster. A 1 stands alone.

Play your first board

1. Open ClusterSum and try the three short playable tutorial examples. You can replay them in Settings.
2. Choose Journey for progression or Daily for today's puzzle.
3. Tap an editable tile to cycle 1–5. Drag up or down to choose a value; drag down to 0 to erase. Clues and decorative blockers cannot be edited.
4. Connect equal numbers up, down, left, and right. Diagonals do not connect.
5. Fill every playable tile so every cluster has its required size.

Read the feedback

Incomplete clusters use neutral styling. Complete clusters show a checkmark. A conflict marker means a group is too big or lacks enough reachable room. Select a tile to see its connected count, such as 2 of 3 connected. This is a local cluster check, not a guarantee that every current entry can lead to a complete board.

Try a move without losing your work

Undo reverses an edit. Reset Board restores clues and hinted tiles; the reset can be undone. Undo history lasts for the current session.

A Hint fills and locks one tile and clears the current undo history. The first three hints in each puzzle are free; extra hints cost 40 coins, shown on the button. A perfect solve uses no hints.

Choose what comes next

Completed Journey boards remain visible until you choose Next Puzzle. In Daily, use the calendar or date arrows to choose another date, including the previous 45 days. Your entries save locally when you leave a puzzle or close the app.

See gameplay and screenshots · Full How To Play guide · Support

iCloud sync in version 1.1 and later

Enable Settings → iCloud Sync → Enable iCloud Sync on devices signed in to the same iCloud account. No separate ClusterSum account is needed. Enable it first on the device whose coin balance you want to keep: that device establishes the shared wallet. Other devices add their saved puzzles and Daily history without adding their old balances.

Journey progress, puzzle boards, Daily history, themes, and the shared coin wallet sync while ClusterSum is open. Haptics remain specific to each device. Play offline and use free hints as usual; with sync enabled, paid hints and streak protection require an iCloud connection. Earned rewards and purchases are reconciled without duplicate credits.

Use Sync Now to request an update and check the status and last-sync time. If both devices edited an unfinished puzzle independently, alternate saves are retained under Saved Board Versions. Finished boards and Daily completions are kept when saves merge. Local recovery copies are retained when sync is first enabled.