If there was a great 2D side-scrolling game about Parkours, it would probably play a lot like Dust Force, although the theme is a bit different: Choosing one of four members of a cleaning squad, you have to rid each stage of all dust, garbage, foliage. Unexpectedly, though, they boast a skill set that would make a ninja jealous. They can double jump, wall jump, dash and run along small portions of walls and even ceilings. Each comes with some special perks: The dudette is much faster than the average dude, the old geezer is slow but can jump really high, and the little girl with the pom-poms has really small jumps, but can triple-jump.
There is combat in Dust Force, although framed non-violently: Some objects or creatures are possessed by dirt and float around, so you have to free them. Hitting these "enemies" adds to the combo counter, and the slower but stronger heavy attack even splashes additional "bonus dust" on the floor. Only few enemies attack actively; most are just there to serve as potential springboards, as each attack not only keeps the character suspended in the air, but allows another double jump before hitting the ground. Continued dusting also fills up a gauge for a screen-cleaning special move.
Each level is ended by beating a particular enemy, although it is always just an ordinary mook. Afterwards follows a stage rating in completion and "finesse". The latter is determined by combo length without losing flow, either by getting hit by an enemy or by taking too long to the next speck of dust. Only cleaning all the dust with no single interruption brings an "S" ranking in both categories, and many stages require absolute perfection to achieve both feats together.
The hub world is a free-roaming affair. From a central "Nexus", you can visit the four areas Castle, Forest, City and Laboratory. Each comes with a lot of doors that can be entered in any order, with the exception of locked gates. This means access to many stages at once, and completing most of them is quite easy. The idea is to keep going at them until you get a perfect rating.
Unfortunately, there is no real sense of progress in the game: Getting good ratings at ordinary stages adds to a gauge that awards an iron key each time it is filled. The iron stages then fill a gauge for bronze keys, the bronze stages red keys. All the time you just get keys to get keys to get keys. The red keys are useless unless one gets all sixteen of them, which requires a perfect rating for every single stage.
Also, while it's fun to explore the stages to find new doors, this also prevents a decent difficulty curve: One iron lock may guard a piss-easy stage, while the next may be a spike-filled death trap. Many stages are much easier with the right character, resulting in a lot of trial-and-error. Dust Force combines solid and satisfying mechanics with cool stages, but it's as if someone just forgot to give it all a proper game structure.