Designed by a large portion of the original Earthworm Jim team, SkullMonkeys is an attempt to return to the classic side-scrolling tradition. There's no Z axis here - just a healthy dose of lateral moving, platform jumping, and head bonking in the tradition of Donkey Kong Country and Super Mario Brothers. Unfortunately, SkullMonkeys doesn't follow the conventions closely enough. Sure, there's some interesting level design, but it's overshadowed by a few design decisions that come close to ruining the game.
Most of SkullMonkey's problematic areas won't become apparent until after the first few levels. In the beginning, the game is a little frustrating but fun, and the novelty of the art design - the game is composed entirely of claymation sprites and clay-molded scenery - makes it easy to deal with the somewhat sketchy controls and hit detection. (The game will be even more enjoyable if you just can't seem to get enough fart jokes in your life.)
But once you make it past the first few worlds, the troublesome controls become a major problem. The vulnerable areas of enemies are unclear. Often, you'll land directly on an enemy's head, only to be killed. Other times, you'll run directly into an enemy without jumping at all and still emerge the victor. This gets more than a little frustrating, but after a while it's only the least of your worries.
The fact that SkullMonkeys is more of a technical showcase than a game is proven by the reliance on huge scrolling objects in the foreground. There are objects that literally take up half the screen - with enemies residing behind them. While these are few and far between, a few large objects sometimes obstruct your view. Sure, it's pretty, but it doesn't add much to gameplay. Still, the technical elements are noteworthy. The game looks really nice, the music is great (especially the bonus-room song), and the levels are diverse - at least visually.
Unfortunately, the visual diversity doesn't translate to playability. Each level - and each world - is just part of a constant string of similar ideas, with nothing to break up the monotony save for a few hard-to-find bonus levels. And the bosses are, for the most part, pretty boring.
But what is most frustrating about SkullMonkeys is that it just wears you down after a while. There are no saved games (only passwords at the beginning of each world - which can be several levels apart). There are infinite continues, but if you choose to continue you lose all of your hard-earned power-ups. Worse still, power-ups don't regenerate in a level if you perish. Say there's a one-up at the beginning of a level, and you get killed about halfway through; in any other side scroller ever in the history of the world, that one-up would be there when you came back. Not so in SkullMonkeys. While this may seem like a petty complaint, it isn't. Side scrollers are inherently repetitive. One of the genre's strengths has always been the ability to make it easy to keep playing until you get something right. With SkullMonkeys, you either have to continue and lose all of your stuff or go back to the beginning of a world and play innumerable levels you've already mastered. It gets old fast.
SkullMonkeys holds a lot of promise, but the designers' attempts to make the game challenging (which is the only possible explanation for some of the design quirks) will only make you feel as if they truly don't want you to continue playing. And after a while, you'll be more than happy to oblige.