Zuma is a game by PopCap, and that should really tell you all you need to know. It’s neatly presented and brightly coloured, the gameplay mechanics are simple and repetitive, and it’s addictive to the order of making Colombian drug warlords slap their own foreheads and say “Oh, of course!”. It is available over Steam individually for a few invisi-dollars, or as part of a PopCap Favorites (sic) combo pack for slightly more invisi-dollars but you also get Peggle, Bookworm Adventures and Bejewelled, as well as something called Insanaquarium, which isn’t very good.
But: Zuma. It works a bit like this. A stream of brightly coloured balls rolls slowly down a winding trough towards a hole, and if the balls ever reach the hole then all the balls fall down the hole and it’s game over oh noes except you have three lives. In order to prevent this calamity you, as an immobile stone frog apparently on a Lazy Susan or something, must fire more balls at the ones already in the trough. In true puzzle game style, getting three or more balls of the same colour in the row causes them to disappear for some reason and we can all agree that’s basically a good thing and we can get on with our lives.