Let's address this right up front � Robo5 [$0.99] looks familiar. If you took Atlus's PS3 opus Catherine, stripped out the psychosexual drama and replaced boxer-clad protagonist Vincent with a robot, you'd end up with something like this. But say, for the sake of argument, that you wanted to enjoy excellent box-climbing puzzles without being chased by horrifying nightmares. If that was something you were looking for, you'd be well advised to take a good look at Robo5.

But that isn't to say that this is an effortless rip-off. Along with quite a number of stellar box-climbing puzzles, Robo5 boasts a compelling story about a robot seeking its identity. It also has a visual style that's downright charming, in a steampunk sort of way.

Each of Robo5's levels is a journey to the top of a precarious level. Our robotic friend can clamber over boxes, and he can push or pull them. This is all controlled with simple taps and swipes. Usually these achieve what you want, but the game is quite picky about where you tap. You may occasionally find yourself stuck because you've tapped just a smidgen past the nearest box. I'd bet the controls will feel better in the iPad version, due next week, but they're more than serviceable here.

With such a limited skill set granted to our protagonist, one could assume that the puzzles would be simple as well. Not so. Puzzles in Robo5 are governed by one vital rule: blocks will attach to anything you push them against, as long as at least one full edge of both surfaces meet. You can pull a box out and place it over a gaping chasm, but as long as you don't push it right past the edge, it will linger there for you to climb across.

This opens up the possibilities for puzzle design quite a bit, but special blocks take it significantly further. Some blocks can float, while others crumble after you walk on them. Some explode, some electrocute you, and some can't be handled at all. All together, these make for some mind-bending puzzles.

Occasionally Robo5 throws a curve ball. The eighth and final level of each of the five worlds is timed, though rarely tightly enough to be a problem. But the entire fourth world also limits the number of times you can move boxes. Normally time and movement limitations just effect the number of stars you get, but in those levels they're hard limits.

Thankfully, the game has an undo button. This takes you back to the box you moved last. When every push, pull or drag counts, you'll come to love this feature, although it occasionally sets you quite far back.

The star system in Robo5 isn't just there for kicks. At each 20-star milestone, a new diary entry unlocks. These tell you more about LA and LY, the mysterious sisters who help (and hinder) you through your trials. Furthermore, each diary entry has an associated level, and completing it unlocks secret information. This is a mechanic that makes succeeding at levels particularly compelling � do well, and you might earn enough stars to learn something new.

At the time of review, this story is marred by a somewhat sloppy translation. According to the developer, this will be fixed in the first update. But despite the rough edges, this is a story that's worth paying attention to, a rarity on this platform.

I wouldn't praise Robo5 for originality, but I also wouldn't write it off for its copy-cat nature. This is a puzzle game that iOS deserves, and I'm glad to have had the chance to play it. That care and attention clearly went into every part of it (bar the editing) makes me inclined to be a little more generous, and it seems our forum users largely feel the same. Decide for yourself, but be sure to let us know what you think.

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