It's as easy as putting one block on top of the other...
Stack's simple gameplay has you trying to put one block on top of another to make a tower. You start with a square base, viewed from a 45 degree isometric angle, and new blocks of the same size come in from the top right and left of the screen. When the new block is directly above the base, tapping on the screen has it drop into place.
Simple in theory, but not so much in practice. Firstly, every time you are a little off the area of the block that has nothing beneath it falls away, shrinking both the incoming blocks and your target. This can rapidly end runs if you miss big. Fortunately, reaching milestones - such as fifty blocks dropped - does reward you with a slight size increase.
Which it turns out isn't that easy
Then there is the getting timing right, which takes some practice, especially as the pace slowly increases as your tower gets higher. Eventually you are hammering on the screen multiple times a second, frantic to ensure that the now sliver-of-a-block lands on target to continue your run and get a new high-score.
When your current attempt inevitably fails, the camera pulls back to show you the beautiful tower you have created - filled with slowly shifting pastel colors that look fantastic against the matt background. Oh, and if you are competing with friends your score is automatically uploaded to the leaderboards.
Pretty, mindless fun
There isn’t much too Stack, but it is enjoyable for a while, pretty, and free. Providing you are willing put up with the constant ads at the bottom of the screen - and the occasional out-of-place splash screen - you can certainly have some fun with it.