I like this game. I wish there were extensions!
I would like to clarify a couple of things:
1) Is there a max number you can reach? I've never got higher than 8 afaik though.
2) Do the drop rates increase over time?
3) Can you only pick up blocks horizontal to the character?
WISHLIST: I would love a version with a larger play area but don't want the blocks to be any smaller. A version where once the blocks reach a number they disappear. A level mode (or vs mode like Puyo Puyo). A mode where drop rates don't increase so I can see how far I can get on my own skill). A mode where you don't get crushed (or as easily).
I haven't got any gray blocks, so I can't comment on those.