Timelie is a seemingly unassuming puzzle game. It backs up a Prince of Persia-style tumble down a collapsed passageway by going backwards in time. But scraping that timeline is not the real goal, and there are some clever surprises that are worth sitting down and playing through once or twice.

"Timelie," which both my brain and computer frequently autocorrect as "Timeline," would have been considered indie-chic in 2008, but its appearance is bland today: a right-angled world without clarity or texture. It's charming but boring. The narrative is vague and sleepy, littered with iconography (birdcages, locks and keys, etc.). I was never gripped by the metaphors, but I didn't need a strong motive to escape the cartoonish girl from the robot-protected maze. After being subjected to volumes of tedious Robin Hood fables, I was glad for a puzzle game that satisfied me with voiceless cutscenes and sad-sounding bell music. Cats are cute, though, and cute cats are always welcome.

The object of the puzzles is to take the girl, and sometimes the cat, to the exit of each room in a medical science facility with a general atmosphere. Your path is blocked by closed doors and patrolling robots that follow the protagonist and smack him on the head when they find him. Since sound has nothing to do with stealth, you can stand right next to the robots as long as they don't find you.

Here's the temporal twist: as you watch the YouTube video, you can scrub back and forth through the timeline and observe the robot's patrolling pattern. At any point in the timeline, you can issue new commands to the girl and the cat, or erase commands already issued. If either is caught by the robot, the timeline ends there and can no longer be pushed forward into the future.

This is a very good way to include fail states that are not fail states. If you make a mistake, just rewind and change a few clicks and try something new. If your plan was wrong from the very first move, you would have to go back to the beginning of the level and start over, but you rarely feel bored because you don't have to watch your plan play out in real time. But you rarely feel bored because you don't have to watch your plan play out in real time. If you drag time into the future, no, you just know that if you do that, the robot will hit her over the head.

Very minor complaint: the interface is at the bottom of the screen, and on my 27" monitor it has disappeared from my concentration so much that I didn't notice for a while that there is a handy icon that tells you whether you are selecting the girl or the cat (the white glow around it, not communicate as clearly as possible); I think PC game interfaces should either leave a little space between important information and the edge of the screen or be customizable, but this is an annoyance at best, so don't be fooled by my UI obsessivism.

In addition to predicting patrol patterns and staying out of sight, the girl and the cat must work together to find ways to distract the guards and open doors for each other. The cat meows to attract bots, and the girl can collect orbs to repair parts of the level. More complex puzzles involve manipulating the bots' patrol patterns with tactical meows, bots trapped in rooms with decoy maneuvers and switches, and a harrowing dash through the level with walls that evaporate over time and wipe out the level.

The puzzle solutions are subtle and somewhat frustrating. Sometimes you have to guess whether the girl will move a certain number of spaces to get out of the bot's sight, or whether the cat meowing one square over will have a completely different result. Otherwise, it's tutorial-level easy. But many of Timelie's stages hit the sweet spot between mechanical and conceptual complexity. And near the end, something really tricky happens, in a non-spoilerish way.

Suffice it to say that "Timelie" provided some good time travel tricks and wrapped things up before getting stale during its four-plus hour running time. I was a little disappointed that the last part of the film didn't quite live up to my expectations, and some of the levels in the second half, while conceptually cool, are not that much fun to unravel. Overall, Timelie is a well-made puzzle game. The somber atmosphere is perfect for killing time before bed, and this is how I ended up playing through the night and staying up later than I had planned.