Katamari Damacy is a special sort of game. So special in fact, that it sidetracked me from writing this several times, playing the game in an absent-minded daze, marvelling at how 塊,the Kanji for katamari, already looks like a small prince rolling stuff up. It worms itself inside your brain by giving the mundane a unique sort of whimsy.
Whimsy, silliness and fun on first glance seem like something unrestrained and purposefully difficult to capture, but Katamari's game director Keita Takahashi made these feelings into substantial pillars of the design philosophy that informs all of his games. Katamari is meant to convey novelty, ease of understanding, enjoyment, and humour, all in a neat little package.
At first glance, there doesn't seem to be much to Katamari Damacy. You and your katamari (Japanese for "clump") are dropped on a random map where you then roll over items to add them to your little ball. What items? Any items. The absence of restrictions is very freeing - if you see something on screen, odds are you can roll it up at some point. The few limitations that do exist make sense: you can't roll into something bigger than yourself, that would ruin the whole equilibrium of your ball. If you bump into any obstacle full force, items are inevitably going to break off of your katamari. Maybe it's an odd core idea for a game, but the mechanics and aesthetic aspects of Katamari are the equivalent of a gentle shrug, the very essence of "why not". Roll with it.