Puzzle-platformers are all the rage in the world of indie games. Perhaps it's because they're so accessible for so many different kinds of gamers - or because they're a genre well suited to exploring unconventional narratives. Whatever the case, intuitive design is central to the success of these generally more minimalist games. Thankfully, Rocket Pocket Games' Shiftlings has a surplus of this. Though it has a number of serious issues that keep it from meeting its full potential, there's a level of cleverness and creativity here that other developers should take note of.

The title follows two clumsy aliens attached by a tether-like tube. Thanks to one of the dopey extraterrestrials drinking an insane amount of Black Hola Cola, the two are able to - ahem - exchange the gases using the tube, thus switching who is inflated like a balloon and who is able to walk through smaller spaces at normal size. Players can choose to tackle the adventure alone, where they will switch between control of the two characters, or cooperatively tackle the five worlds of tricky puzzle-platforming.

These puzzles are often devilishly clever, and the level design gets an impressive amount of mileage from the simple inflation-switch mechanic. As with any well-crafted puzzler, the way simple concepts are introduced and developed further in subsequent stages is satisfying and intuitive. There's a certain subtlety to it, as well - with almost no hand-holding involved, the player is responsible for devising their own solutions and recalling those processes when a similar situation arises later.

The challenges are particularly stiff when going after the game's optional "Black Hola Cola" collectibles, which unlock an extra level in each world when collected. Nabbing these items makes players go the extra mile in stretching the concepts they've learned, and is consistent with the rest of the title's great design. It's nice to see developers make this sort of thing a serious task for skilled players, rather than create the usual sprinkling of collectibles not far from the main path.

With a solid repertoire of creative stage designs and a reliable central mechanic, your initial impressions of Shiftlings are likely to be positive. Unfortunately, one area where the game suffers is in its ability to hold your attention; though it makes a valiant effort to introduce new ideas at a regular pace, its central conceit remains a repetitive, wearying one. In the same vein as many mobile titles, it's best to enjoy these puzzles in small bursts.

A few technical niggles get in the way of the fun from time to time, as well. The load times between levels, for example, are a bit long considering their humble size. In addition, in stark contrast to the instinctual nature of the puzzle-solving, the controls come off as a bit unintuitive. That's not to say there's anything inherently wrong with the way the buttons are mapped, but they're not set up in a way that helps recall their functions. Pressing the wrong one is a common issue that many players will likely have to contend with.

Shiftlings' presentation is pleasantly cartoonish, at least in the visual department. The characters are animated in a bouncy, goofy way reminiscent of your average CGI cartoon, and there's certainly no lack of colour in any of the game's five worlds. Some of the levels are rather impressive in scale, as well: the spectacle of the "boss" stages, where you can see a zoomed-out view of the giant beings manipulating the environment, are particular standouts.

Unfortunately, this quality of presentation doesn't quite make it to the audio realm, where there's a nagging sense that those involved were trying too hard. The quirky music isn't too bad, though it gets a bit too repetitive and irritating when trying to brainstorm puzzle solutions. On the other hand, the ubiquitous catch-phrases uttered by the hosts of the game's TV show framing device are an unfunny assault on the senses. "All alliteration aside, positively perfect playing, peeps!" is almost cute the first time you hear it, but ear-bleedingly annoying by the eighth sound byte. If you intend to enjoy the game for any significant amount of time, it's not a bad idea to mute these loudmouths. This is particularly disappointing because it's the only real use of the framing device outside of a few lame cutscenes - setting a game inside a TV show is a great idea, but here it's a wasted gimmick and a missed opportunity.

Conclusion

Shiftlings boasts some masterful level design for puzzle-platforming fanatics, and its intuitive, hands-off way of teaching mechanics will come as a pleasant surprise for those unimpressed with modern games' tendency to overuse tutorials. There's a lot to like, to be sure, but Shiftlings comes up short in a few areas where it really counts. A repetitive central mechanic, controls that fight your instincts, and some truly annoying voice acting all stand in the way of a wholehearted recommendation. Patience is a virtue, and those who have it in spades will likely find the outstanding stage design worth enduring some of the other frustrations.