How to play
- Goal
- Match ordered run clues, join all Dark cells through their sides, and avoid solid dark 2 × 2 squares.
- How it ends
- The chart finishes when every cell is Dark or Pale and every run, connection and square rule holds. Undo and Erase allow corrections.
- Record
- Your first unassisted finish keeps its time for this chart; later plays are practice.
- Read row clues from left to right and column clues from top to bottom. A number gives the exact length of one maximal Dark run. Separate runs with at least one Pale cell.
- A question mark means exactly one positive-length run. A star means zero or more runs, each with its own positive length. An em dash means no Dark runs.
- All Dark cells form one nonempty side-connected stream. Diagonal contact does not connect cells. No fully Dark 2 × 2 square is allowed.
- Branches, larger rings and enclosed Pale cells are allowed. Pale cells need not connect to each other or the border.
- Choose Dark, Pale or Erase; tap or drag. A released stroke is one Undo. Inspect stream describes marked connections without painting.
- Escape, resize, pointer loss or a second finger withdraws an unfinished stroke. Restart retains the first clock; reload retains marks and Undo, and resumed finishes stay local.
Controls
| Mouse / touch | Choose Dark, Pale or Erase; tap or drag across cells |
|---|---|
| Arrows + Enter / Space | Move focus; paint the focused cell |
| 1 / 2 / 0 | Select Dark / Pale / Erase |
| Delete / Backspace | Erase the focused cell |
| Z / Y | Undo / Redo |
| R / Restart | Confirm clearing ink; the first clock keeps running |
| Escape | Cancel an unfinished stroke, close a dialog or return to the atlas |
| Controller | D-pad moves; A paints; X cycles brushes; Y erases; shoulders Undo/Redo; B cancels/back; Start settings; Back rules |
Tips for Cross the Streams
- Fill a line A run as long as the line occupies every cell; neighbouring stars then stand for zero runs.
- Prevent a square Three Dark corners of a 2 × 2 square force its fourth corner Pale.
- Leave a gap Two separate runs need at least one Pale cell between them.
- Keep a bridge A cell that is the only remaining side connection between Dark groups must be Dark.
Questions about this game
Does a star count cells?
No. It replaces zero or more whole positive-length runs.
Can star runs differ in length?
Yes. Each run has its own positive length.
Do corners connect Dark cells?
No. Only shared sides connect them.
Must Pale cells connect?
No. Only the Dark stream must be connected.
Are dark rings allowed?
Yes, provided no solid Dark 2 × 2 square forms.
Can replay improve my first time?
No. A saved first finish remains unchanged; replay is practice.
All charts are open. Reload retains marks, Undo and the original first clock; resumed finishes stay local. Practice reopens fresh and preserves your first time.
Watch how to play
About Cross the Streams
Paint an amber river mosaic using ordered run clues around its edges. Keep all Dark cells joined through their sides and prevent solid dark 2 × 2 squares.
All 160 original charts are open: fifty 4×4, sixty 5×5 and fifty 6×6. Every chart has one solution and can be solved by logic.
Your first finish keeps its time. An uninterrupted verified first solve can claim the named fastest time; replay is practice.
