Number Stacker, for better or for worse, looked like a different kind of game. After playing it I'd have to say it has a little of that Tetris feel, but falls short of being as good as Tetris for one key reason that I will get to later.
For a start the game, unlike many, does include instructions although they are in broken English. The gist of the game is that the numbers are falling slowly from the top of the screen and if/when they reach the bottom you lose life as shown in the life meter. You have five number across the bottom that you can stack on these numbers provided that the number isn't more than 1 off of the number you are stacking on. For example, if it's a 5 you could drag a 4, 5, or 6 onto it and it will become that number. Stack three numbers onto one spot and you eliminate it saving your precious life meter any hard. You also can also flush the numbers along the bottom with the little R button and get five new numbers if you don't see any useful (or possible) plays. As you progress you'll advance in level and get addition flushes to help out your cause. You can also pick up bonus points by dragging an identical number or color onto a valid spot.
The games graphics are basic, but the controls work well... a simple drag from a number along the bottom onto a number as illustrated had no problems. This game falls short, though, as the game's engine is apparently random and all too often I had 3 8's coming down the screen with a 1, 2, 4, 3, and 6 as my numbers or a 6, 7, 9 and 0 falling while having 3 1s and 2 2s as my choices. The flush option gave me an out sometimes, but as it is limited in use I found that as the game progressed I was frequently left between a rock and a hard place. A no win situation = no fun. The game engine really needs to be smarter and ensure that there's always a play to be made... maybe the one play at a time and the thinking that is involved might warrant flushing as a 'best move' still making the flush option have value, but those impossible situations really were annoying.
In conclusion, I found myself really enjoying this game initially and felt my brain processing all of the options, but then when it became obvious that I couldn't do anything, but watch the numbers drop and hope for a good 'next' number it became a nuisance. There's untapped potential with this idea, but it needs more work and some catchy music. I'll also offer to improve the instructions and eliminate the broken English for free if the developers want to contact me. As is I can only give this 2.5/5 stars.