I've learned to try first and it worked fine for me for the first few levels so I bought it. But once I reached level 6-8 I discovered one can't complete it without using the power-ups and they don't work on my computer. Indications in the forum are that the third in the series may work better. I am old and prefer to play un-timed games so found it got very boring to play level 6 over and over and over again because I couldn't finish 6-8 in the time allotted.
It worked long enough so that I bought it, but won't go past the first set of games. I have OS 10.5 and have learned to test with download before buying so am very irritated that this one worked long enough to seem okay but is a waste since it can't be played beyond the simplest level which is quite routine and rapidly becomes boring.