What is Kirby? Yes, I know he's a pink blob, but what exactly is he? Mario's a human being. Donkey Kong is an ape. Link is an elf-like boy. What is Kirby? WELL? WELL?
Wikipedia says he's (he's definitely a he, isn't he?) a "small, pink, spherical creature with large red feet, stubby flap-like arms and trademark pink cheek-blushes". According to the instruction manual for Kirby Super Star Ultra, the DS remake of the 1996 SNES platformer, Kirby is a "gourmet who uses his big mouth to inhale and swallow almost anything". I suppose that's as good a description as I'm going to get.
Now we know what Kirby is, we can get on with the good stuff. What is Kirby Super Star Ultra? The answer is that it's a cute, cuddly, old school 2D side-scrolling platformer. Kirby can move left and right, jump, fly and, as the instruction manual says, inhale and swallow almost anything.
That last bit, as anyone who's played one of the many Kirby games Nintendo has released down the years will know, is what makes the Kirby games unique. When Kirby inhales an enemy, he can swallow them to assume their abilities and change his appearance. Or he can make a helper by what looks like regurgitating them.
There are absolutely loads of different kinds of enemies, each with unique abilities - so Kirby, in effect, has access to tons of abilities. He can hang onto walls as a ninja; fire a powerful arcing beam attack; fly using a jet pack; chuck bombs; smash with a hammer; slice with a sword; punch and kick as a fighter; turn enemies into blocks of ice and even cook every enemy on screen, turning them into recovery food. The sheer number of possible abilities is quite astonishing.
What's disappointing is that the game doesn't riff off of this mechanic. You're almost never required to employ smart use of copied abilities. Only The Great Cave Offensive game mode, which sees Kirby lost in a deep cave as he searches to find 60 hidden treasure boxes, challenges you in this regard: some treasure boxes are placed so that certain copy abilities have to be used to open them. Bar that, though, it's irrelevant what copy ability you currently have equipped. The upside, however, is that you're motivated to hunt down every last enemy just so you can see what power they grant. It's a classic "gotta catch 'em all" affect.