Unpark

Unpark is a free unblock car puzzle you play in your browser: a packed parking lot seen from above, a red car stuck in the middle of it and an exit gap at the end of its row. Every car and truck can only slide forwards or backwards along its own lane, never sideways and never turning, so the only way out is to work out which vehicle has to move first, which one that frees, and in what order the whole traffic jam untangles. It is the classic sliding block puzzle on a 6×6 grid, the rush-hour-style parking jam puzzle, drawn as a bright cartoon parking lot with chunky cars, box trucks and buses, and cut down to a quick two-minute run.

A run is a string of lots against one clock. The first lot needs just two moves: slide the car that blocks the red one, then drive out. As soon as the red car zooms through the gap the next lot rolls in, and every lot needs exactly one move more than the one before, from easy warm-ups through medium and hard jams to expert lots with fifteen moves; from the fourteenth lot on, every lot needs fifteen. Every lot has a known best solution, worked out by a computer search when the puzzles were made, so the game can show you the par for each one: a move counts every time a vehicle slides somewhere new, however far it goes.

Scoring rewards both clean thinking and speed. A lot pays 100 points for every move of its par, so later lots are worth far more, and solving it in exactly the par adds an efficiency bonus of half as much again, minus 50 for each extra move. Undo takes back a slip but never refunds the move, and the hint, which charges for ten seconds, makes one best move for you at the cost of that lot's bonus. Speed pays through the clock: the faster a lot falls, the sooner you reach the next, better-paying one. Every seed deals lots of exactly the same difficulty in every slot, so every run and every leaderboard is fair, and top runs are replayed on our servers before they count, which puts Unpark among our competitive games.

The controls are made for a thumb. On a phone, press on any vehicle and drag it along its lane: it follows your finger over the free stalls, stops against whatever blocks it and snaps into place when you let go. On a computer, click and drag the same way, or play with the keyboard: the arrow keys select and slide vehicles, Space picks the next one, Z undoes and H takes the hint. It plays just as well on mobile as on a PC, with nothing to download.

If you enjoy logic puzzles where one good move opens up the next, Unpark sits alongside the other puzzle games and the short challenges on the brain games page, and it is the thinking member of our car games. A run lasts two minutes, so it is also one of our quick games and a good pick among the free games to play at work. New to parking puzzles? The first lots teach you everything, and after a few runs you will start to see the patterns: trucks that must go down before cars can go up, and the one car that unlocks a whole row.