There are lots of games that are similar to lots of other games. This is doubly true in puzzle games as there seems to be a gazillion variations of just a few concepts. In that tradition, Aqua Rush can be described as upside-down watery Tetris where you control the shape of the piece. If you saw the movie "The Abyss", it's kind of like the watery dudes from that piecing themselves together.
Another description could be a watery variation on Block Hole - a GOTD from way back that I love where you shoot bullets to fill blocks up as they come downward. (Of course not very many folks know what Block Hole is).
So, like Tetris, pieces float (not fall, it's upside down) upward toward an irregular wall of pieces that you have to fill in. Fill a row straight across and it disappears (blows up). Then, the watery pieces left over float further up and may fill in more whole rows - thus a chain-reaction kind of event. Your goal is to uncover/blow-up enough rows to reach the end (a rocky-looking outcropping where the water ends). Of course meanwhile, as you fail to eliminate blocks/rows, they grow downward toward you. If they reach the bottom, you die/lose.
BUT, here's the compelling part of the game... you control the shape of the pieces. Each piece is three columns wide and you have three buttons - each corresponding to one column of each new piece that forms. Every push of a button extends the length of the watery piece by one unit IN THAT PARTICULAR COLUMN (i.e. the left button adds to the left column). So, as the piece floats upward, you are frantically pushing the buttons to add length to the columns to match where it is going to fit in. Meanwhile, you have a joystick to move the piece left or right (or up - which makes it go faster). So, you move the piece around, add length to any or all of the 3 columns and try to fit it into the existing puzzle wall. It's easy at first and gets frantic quickly.
There are some tricks you learn. Pushing multiple buttons at once works. And also, more importantly, you have a second to continue to add length once the piece fits in and settles. Even though it has stopped, you have a moment to quickly add pieces where you want to fill in gaps. This becomes VERY important quickly and will bail you out often.
There's no rotating of the pieces and no colors or other distinguishing characteristics. They all function the same way, although, just to screw you up, when they first appear, some have different lengths in the 3 columns to start with.
Scoring is cool - as it is based on how quickly you finish the round. If gives you a rank, a grade and a bonus. I do love me some data!
The game is fairly recent - 1999. As such, the graphics are very nice. The backgrounds don't mean anything to the game, but you can choose among several that are active and look like you are scuba diving (again with the water theme).
It's frantic puzzle fun and compelling/frustrating in the way that it should be. Funfruspelling, if you will.