See, if you look at the page for Koloomn/Ultimate Block Party, it lists the Japanese version as just Kollon, the same name as the arcade version. However, there's also an entry for a later version called Korokoro Kollon, so you'd assume it's an upgraded version not released in the West, right? You're close! Korokoro Kollon is an upgraded version, as it adds wifi play and several extra modes including the Tutorial, Puzzle Challenge, Training Solo and Campaign... Basically, the modes in Koloomn/Ultimate Block Party. It's supposed to be the other way around- . The PSP game just called Kollon is a (mostly) straight port of the arcade game, only adding in Vs. CPU mode and the characters that appear in it. So, in case you were worried, you're not missing anything by going for the Western releases. Although I'd go for Koloomn just because the title screen's better.