I’m not usually a fan of toilet humor, and Wimp: Who Stole My Pants (Free) takes place in a land reached by toilet, more or less. You hunt down stolen underpants, platform through toxic sewage and solve puzzles to claim toilet paper rolls. This hasn’t triggered a moment of squeamishness, though. I’ve been far too busy touring the sights and sounds of the world of Wimp, trying to get every single one of those rolls into my collection and taking in some fantastic puzzle-platforming.

Wimp is one of the better platformers on iOS, but you wouldn’t know it from its structure: 60 levels laid out in a menu, a three toilet-roll ranking system, and a handful of thematic worlds to flip between. It’s dull, but it works, and lets us focus on the meat of the thing — the many clever challenges Flexile Studio has prepared. Most of them surround box pushing or button pressing, but that doesn’t mean they’re boring.

Each of Wimp’s worlds alters that game. The first, the noxious Junk Quest, gives Wimp his default goo ability: sticking to stuff. Tap the power button to stick him to any safe surface, and he’ll hang there until you tap him off. It’s a useful ability, best for clinging to moving objects or throwing your weight around. The second world, Teddy Quest, is cute and fluffy. Wimp’s new power isn’t, though: he can turn into a fireball that can float in midair and fire itself through certain obstacles. Like his goo form, this gets you into places you couldn’t otherwise reach.

The third is the coolest, and the most Portal-esque (if you’re going to take inspiration from any game, that’s a good pick). Rusty Quest lets you put a blank copy of little Wimp in one location, and pop back to it at the press of a button. Stick one on a platform and send it through a deadly gauntlet without you. Or you can place one under a distant toilet paper roll and dive off a cliff, using your momentum to fling you up to new heights. The mechanic is fun, clever and well-used.

Otherwise, it’s small things that set Wimp apart. Animations, for instance—for a barely mobile green blob, Wimp is darling when you let him idle. Backdrops add a hint more character to already-interesting level designs, with cloud dragons floating by and mysterious trains tottering in the distances. The worlds stay true to their themes with detailed platforms that are rusty or fluffy in turn, and boxes that look soft or solid or unpleasantly squishy.

This attention to detail does fail on occasion. There is little fun to be had here without trying to collect the three rolls of toilet paper tucked away in each level. Puzzling out how to reach them or find them makes up most of the challenge. So it’s disheartening to realize that collecting a roll is not quite the same thing as keeping it.

There’s a reason for this: many of the puzzles require that you find a way to collect a roll without, say, falling into the pit of flame directly below it. Or smashing into the blades that line the way out. If you could just grab the rolls and die, most of that challenge would be lost. But as a tragic side effect you can pull off great feats of platforming, collect a roll, make it out unscathed, then die nearby in an unrelated jump and have to do it all again. This is Wimp at its least charming.

I’ve also had an ongoing disagreement with the controls. For the most part they’re brilliant, and do exactly what you’d want. Jumping feels right, movement is precise, and anything that isn’t working out positionally can be adjusted in the control menu. But the flame power-up in the second world has me seeing red on a regular basis.

All the power-ups are fussy from time to time, but the flames are consistently awkward to handle with virtual controls. You need to jump, tap the flame button, and then tap the direction you want to go once Wimp is hovering in place. This is well enough when you’re not under pressure, but it can be a nightmare in tight areas or while moving. The game can’t take it easy — that wouldn’t be much fun — but, the Teddy Quest levels don’t always work out all that well when the going gets tough.

Most of my time with Wimp has been great fun. The puzzles are clever often enough to feel rewarding, and the platforming is responsive and well-controlled. There are a few rough points, moments when the puzzle design struggles against the game’s limitations and leaves the player to feel the pain, but not many. Not nearly enough to keep Wimp: Who Stole My Pants from being anything other than highly recommended. You might say chasing undies isn’t your thing, but Wimp will surprise you.