I know I've posted game links before, but oh my, you need to be careful with this one. It's kinda tetris-like in that you're dropping pieces from above, but all the pieces are single units with numbers inside them. To get the pieces to go away (blow up), the number must match either its horizontal or vertical positioning. Then of course there are the blocks without numbers. Those you have to break by having numbered blocks blow up next to them.
Give it a try... er... when you don't have anything to do for a while :)