As you make your way through Sentinel's tiny worlds, you'll find diverse, well-crafted brainteasers that are admirably challenging, usually without going over the top. You'll get to solve puzzles that challenge your skills of spatial visualization, pattern recognition, tone memorization, and more, sometimes in the same puzzle. You'll work your way through a maze with moving parts, match moving patterns on giant flowers to coded control panels, and of course align lots of bridges (a clichÃ© in need of rethinking). Optional onscreen hints tell you your basic goals for each puzzle without giving away too much, a welcome feature all adventures should offer.
As interesting and challenging as the puzzles can be, they're far from perfect. Inventory puzzles are conspicuously absent, so it's all about manipulating strange machines. The puzzles feel rather arbitrary, too. You get the distinct impression that Detalion crafted the story simply to justify a big bundle of puzzles, rather than creating a unified gameworld first and then inventing puzzles to fit it. Then again, considering the quality of many of the puzzles, that's a fault you may be able to live with.
Some flaws are harder to swallow, though, even for dedicated puzzle fans. Some of the puzzles are relatively easy to figure out, but often a real chore to carry out. Sometimes it's hard to see how certain moving puzzle pieces are aligning in the 3D world since the game occasionally forces you to stand in one place as you work the puzzle's controls. Just as problematic is the way you might look at a puzzle, quickly say, "Eureka!" (or something less geeky), and then slump in your chair as your realize just how much traipsing back and forth you'll need to do to actually complete the challenge. Because of the way puzzle components are often spread far apart, the requisite walking can feel interminable at times.
You'll also encounter way, way too much repetition. For example, there are a handful of nearly identical puzzles in a strange fishing village that require you to move colored ropes into particular positions. After you figure out how the first set works, the others are just tedious busywork. It gets even worse later, on a series of volcanic islands where you have to align five bridges according to identical principles. Once you figure out what you're doing with the first one, you're left with an hour or so of walking back and forth, taking notes, and pressing button after button. It's pure drudgery. One such bridge would have been enough. In later segments, Sentinel similarly starts with good ideas and then drives them into the ground through loads of repetition.
Bizarre machines are commonplace in Sentinel.
Still, despite such big flaws, the overall quality of the puzzles is a cut above that in many Myst clones, and so too are the graphics. While Detalion's last game jumbled a bunch of pretty scenes together more or less randomly, Sentinel boasts a lot more cohesion, at least within each of its worlds. Not only are the graphics technically assured, with nuanced textures and believable character models (not that you see many), but each area you explore also fits together well. In the fishing village, some walkways are made from nets, and the puzzles are crafted from other simple materials you'd associate with seaside living, like rope and shells. By contrast, a strange floating observatory dazzles the eye with massive spinning machinery and metal walkways perched high amid the clouds. It's too bad Sentinel's audio doesn't match the quality of its visuals: All you get are some sparse sound effects, generic ambient music, and middling voice-overs that can't hide the clunkiness of the game's script.
Sentinel is also quite short and could have used more polish. Sometimes voice-overs unintentionally overlap or don't match the optional subtitles properly. Still, despite its problems, Sentinel can be good fun for a thinking gamer eager to analyze, ponder, and take a heck of a lot of notes. If you want memorable storytelling, characters, and exploration in your adventures, give Sentinel a wide berth. But if you're really just after interesting puzzles, and you can put up with a whole lot of repetitive busywork along the way, you'll want to test yourself against Sentinel's challenges.