I have Kororinpa and it's pretty fun. I thought it would be like marble madness but it's more leisurely. AFAIK, there's no enemies trying to kill your ball and no time limit. However the point of the game is to finish the level as fast as you can. So far the levels haven't been that big. If you take your time, you could finish them in about 2 mins. Lots of unlockables in the game though. Mostly other kinds of marbles/balls and bgms. Played about 15-20 levels so far. Seems like there could be way over 100 levels too.