I'd love it if extra keys could be used later on. I think I had seven keys, opened the gold box, was granted 10 more, then a red gave me six more, by the time all the boxes were open I still had keys left over. They disappeared by the time the next opportunity to use them came up.
Definitely love this game; the only thing I'd suggest adding is a darker background or bold X for the X tiles. Great game, took my time and completed every level.
Cippo- it's a money gummy. If you play the game from the beginning, the first time you hit one of the gummies either holding a bag or the green bear, it shows images of both and explains that hitting one gives you more money.
Way too addicting, I love it! I'm still failing after the 100k mark, but hey, it's a great game. (And I love the graphics, reminds me of some of the old pc games I had as a kid)