Grimm (a.k.a American McGee's Grimm) was originally released on GameTap in weekly episodes, and is made by several of the same people who made American McGee’s Alice and Alice: Madness Returns, principle member being American McGee, obviously, but also the writer and one of the main voice actors - more on that later. The artstyle is very stylized and a bit silly, but quite lovely, and it fits the theme very well. The gameplay is simple, but satisfying; a somewhat detailed description of which is below.
The game stars a filthy, cynical, sadistic dwarf called Grimm (hence the name), who despises the trend of prettying up fairy tales for kids, and makes it his mission to return them back to their dark origins, or at least his own spin on their dark origins. Grimm, along with every other character in the game, is voiced by Roger L. Jackson, whom you may know as the voice of Ghostface (Scream films), Mojo Jojo (the Powerpuff Girls), the Cheshire Cat (McGee's Alice), Anton Sokolov (Dishonored), etc. etc. As such, despite being only one person, the voice acting is varied and top notch, if hammy, and is one of the highlights of the game, along with the well written dialogue and dark sense of humour. The game doesn't take itself very seriously, and it's all the better for that.
Grimm is made up of a series of self-contained episodes that take about half an hour to an hour to complete, each one based on a particular fairy tale, some well-known, others not so much. At the beginning and end of each episode you watch a puppet theatre narrated by Grimm, the first one being a cutesy and inoffensive version of the tale that he picks apart, the latter one being his own, nastier, gruesome take on the tale. These, as with all cutscenes, are skippable. Between these two are a series of levels or "scenes", based on the events of the tale, and it’s here where the meat of the game lies.
Gameplay-wise, the game is a fairly simple platformer but with a special mechanic; in every level Grimm has a circular aura around his person that can instantly change objects from their original sugary cuteness, to excessively dark and grotesque. The living creatures and people of the land (referred to as "cleaners"), valiantly try to stave off Grimm's corruption by converting objects back to their lighter selves. Their efforts are pretty much in vein, however, as Grimm can convert objects far more quickly than they do, so they function more as a nuisance than a real threat.
As Grimm converts more objects, he becomes more powerful, which is represented in-game by his "Dark-o-Meter". Gaining levels in the Dark-o-Meter gives Grimm a larger aura, allows him to jump higher and run faster, and most importantly, convert bigger objects and eventually the cleaners themselves, which renders them powerless. To progress through each level, Grimm must convert certain indicated objects to their dark equivalents, which usually requires filling up the Dark-o-Meter to a certain point. There is no fail state, and though Grimm can die through environmental hazards such as water, he respawns immediately and there is no penalty for dying, so playing through the game is a fairly straightforward and relaxed affair, though there are medals available for speedrunning levels, if you're into that sort of thing.
Some episodes spice things up by introducing powerups, and some levels are more platforming-heavy than others, but other than that the gameplay is pretty much the same throughout the series. One might think this could get boring fast (and for some it might do), but in my opinion it's kept fresh by the sheer variety of objects that can be converted. Every single character, object, and piece of the environment has a light and dark variant, and each episode has its own original setting which introduces a lot of new ones. Much of the fun comes from seeing how each new cutesy object/character warps into a twisted and disgusting parody of its former self (and if you manage to collect all the "secrets" hidden in an episode's levels, you can see the episode's Gallery, which allows you to look closely at light and dark variations of every object from any angle).
There's also something viscerally satisfying about the way Grimm converts things; as your power increases you may begin to feel like a perverse demigod as the land curdles all around you, and the fact everyone is powerless to stop you and you cannot be killed just adds to that. It's fun to look back at your handiwork at the end of each level and see how almost unrecognisable the land is from its former self.
As for the negatives, the gameplay is, as said, simple, and may be too much so for some people. The game was made quickly and on a budget, and it shows - the animation is often quite stiff and there's a certain lack of polish, but fortunately the artstyle makes this not too much of an issue, and it does improve somewhat as the series goes on. While the voice acting is good, it can get rather repetitive at times, as can the music, although each episode has a different soundtrack which prevents you getting too sick of it. Camera is serviceable but a little restrictive; I would have preferred to be able to look up and around a bit more to see things, as that's the focus of the game, though in the later episodes a new wider camera option is added that helps with that. The fact that it's in episodic format results in some oddities, such as later episodes having slightly more features, and settings (e.g. screen resolution) not being transferred between episodes, so you have to re-set them each time you play a new episode. Finally, there may not be a massive amount of replayability once you've been through each episode, unless you wish to get the timed medals and/or find every secret. None of these negatives have been a major problem for me, though.
So, to sum up, if you're only looking for deep, strategic and/or very difficult gameplay, this game probably isn't for you. If you'd enjoy a more laid-back experience that you can dip in and out of, enjoy black humour, and perhaps have a passing interest in fairy tales, you could do a lot worse than Grimm.