Collect numbered tokens and reach the door, but only an exact sum unlocks it.
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How to play
Walk your avatar around the grid scooping up numbered tokens. The exit door, marked by a green ring, stays shut until your collected tokens add up to exactly the quota. Overshoot and you can drop a chip from your tray to get back to the right total.
Plan a path that gathers tokens summing precisely to the quota.
Grab too much and drop a chip from the tray to recover.
Clear levels using fewer moves to score better.
Difficulty rises across a run of levels.
Controls
Desktop: move with Arrow keys or WASD, or click an adjacent cell to step there; click a tray chip to drop a token.
Phone & tablet: tap an adjacent cell to move and tap a tray chip to drop a token.
Game modes
Daily seeded run or endless Practice; you can restart the current level or start a fresh run any time.
Tips & strategy
Add the quota up backwards, decide which tokens you need before you start walking.
Leave a flexible small token uncollected as a buffer in case you overshoot.
Shorter routes score higher, so avoid doubling back for tokens you do not need.
What you'll learn
Pencil Patrol turns a grid-maze chase into mental-arithmetic practice, where reaching exact target sums is how you clear each level.
For parents & teachers: arithmetic fluency hidden inside a maze game.
Origins
Collecting tokens until they total exactly a quota, with the option to drop one when you overshoot, is the subset sum problem walked around a grid.
The original allowance is the drop, which lets you back out of an overshoot rather than restarting.
Subset sum is a genuinely hard problem in general, which is why the puzzle stays interesting at small sizes: there is no procedure that beats searching, and the route you walk commits you to a partial sum before you can see whether it can be completed.
About Pencil Patrol
Pencil Patrol is an original free browser game from PlayPendium that turns a token-collecting grid maze into mental-arithmetic practice on exact sums. Play free in your browser, no download.
A free, original browser game on PlayPendium. No download, no install.
