A nice variant on the matching games, with lots of special jewel types, boosters, and levels. But... to advance you have to earn spheres. I was around level 40 when I noticed some levels had NO spheres (should be impossible, you need at least one to pass the level). I replayed those levels and got to about level 80 with 3 spheres on nearly every level when about half my spheres disappeared... and although I've replayed a bunch of the levels, it now seems almost impossible to earn enough spheres. Enough jewels just don't seem to fall. Level 80+ seemed pretty well impossible without in-game purchases, too, which makes me wonder if the jewel shortage is also meant to incentivize buying boosters. It was a pretty fun game, though, before the spheres disappeared.
