The concept of the game is relatively simple. You are a beach ball (and you may think it's hard to identify with a beach ball, but since the little critter makes motions akin to breathing during the game, you'll find yourself sympathizing horribly quickly) and you need to find your way through a dimension of three dimensional puzzles with spontaneously varying gravitational pulls - gravity that changes depending on what your position is. If you're rolling along the ceiling, well, then, the floor has just become "up" and the sky has gravity. If you roll off the ceiling onto the wall... well, you can continue the thought yourself. Basically, you can roll whereever you like, within a few restrictions (I won't describe them, they're very easy to figure out).
The whole game has a stunning set of graphics and fitting music, perfectly suited for this game and no other. It's truly surprising how such low resolution images can create such beauty in Kula World, but truly, a rerelease of the game on a more powerful console is hardly needed. I wouldn't be surprised if this game didn't even push the PSX anywhere close to it's normal CPU usage. (Later added: I now know it did, in fact, use the entire PSX resources and was highly optimized.)