Every once in a while, a Nintendo franchise will attempt to reinvent itself and try to do something different. Sometimes (like in the case of Super Mario Galaxy), the change is for the better. Other times (like Yoshi's Story), the change is most definitely for the worse. Unfortunately, Kirby's Epic Yarn is closer to the latter.
Kirby's first outing on the Wii tosses away all gameplay mechanics that would be familiar to players of other Kirby games, and instead opts for something entirely new. This is because - like Star Fox Adventures: Dinosaur Planet on the GameCube - Kirby's Epic Yarn was originally designed as new IP, but had Nintendo franchise characters "tacked on" later in the development process. According to Iwata Asks, the game's original title was Fluff's Yarn, and starred the character Prince Fluff as opposed to Kirby. Fluff still has a large role in this game - both in the story and as the second player character in co-op mode.
It is difficult to discuss Kirby's Epic Yarn without discussing Yoshi's Story on the N64. Both games use similar patchwork graphics, a picture-book story motif, and contain similar surgical alterations to gameplay in order to promote simplicity (at the cost of possibly alienating long-time fans). In the case of Yoshi's Story, the power-ups, vehicles, most levels and bosses, and egg ricochet shenanigans from Yoshi's Island were removed. Kirby's Epic Yarn removes all of Kirby's flight, suction, and skill-stealing powers and replaces them with a yarn whip, 2-player co-op, and vehicle transformations. In other words, the game removes every gameplay convention associated with any game starring Kirby. The story sequences are done in picture-book style, and they are narrated by a guy who sounds like he's reading to a bunch of seven-year-olds. The game just feels "different", and not in the good way.
Oh, and you can't die. Ever.
Getting hit causes Kirby to lose a bunch of the "beads" he's collected throughout the level. In practice it's similar to getting hit in a Sonic The Hedgehog game and losing a bunch of rings - though Kirby STILL won't die if he is hit without any beads in his possession at all. In order to please the casual audience, Nintendo has managed to make the entire game feel like a "cheat mode". The bosses are very cool, but once I realized I couldn't die, it sapped all the fun out of fighting them. Sure, there are rewards for not getting hit and losing your "beads", but you most likely won't feel the need to seek them out. I can't help but feel like this game was designed exclusively for children. As a hardcore Nintendo fan, I just couldn't get into it - even with the "winks and nods" placed into the game for long-time fans of Kirby.
There are some good points, though. First and foremost, the game is gorgeous. The "world of yarn" springs to life, with different kinds of thread, patchwork, and cotton combining to frame Kirby's world in a way it has never been seen before. This is a technical marvel and one of the few games on Wii where jaggies are a complete non-issue (even on high definition TVs). The game relies heavily on use of 2D and only appears to use polygons when forming the yarn itself.
Also, although the gameplay is not going to be familiar to Kirby fans, that does not mean there isn't a variety of things to do. Quite often, Kirby will morph into different vehicles - a tank, a race car, a fire engine (controllable with Wii remote), even a UFO. These bits of gameplay were some of my favorites, as they show a lot of unrealized potential. One of the few things that kept me progressing through the game was to discover what kind of goofy vehicle transformation would happen in the next level. There are also some minigames and an "apartment customization" feature that allows placement of objects found in the levels into an empty space, but nothing too substantial. The game controls well-enough and does not require the use of the Nunchuck or Classic Controller. Waggle is very limited - which is a good thing. The co-op mode is also fun and does inject entertainment into some of the less exciting sections of the game.
Overall, Kirby's Epic Yarn isn't bad - it's just not that good, either. It's a kids' platformer with great graphics and a story set in the Kirby universe.
But a Kirby game, it is not.