A very interesting game and a very satisfying one at that.
Gameplay: First of all, to move your ship along the track, just move your mouse to the left or to the right or use the directional buttons. This being a rhythm game, you might think that the objective is to collect all the blocks you see. That is a big no-no because the real objective is to create color clusters. To make a color cluster, you need to put together 3 or more blocks of the same color together. If done correctly, you will get a score. The score depends on the block colors you have collected (purple being the lowest scorer and red being the highest) and how big your cluster is. The bigger the cluster, the more points you get. Be careful though because you might overfill a row. Overfill is to fill a row with different kinds of colors with no matches from either the row itself or the row beside it. When you overfill, you lose valuable points and your ship become a ghost for a period of time. When you're a ghost, you cannot collect any blocks. When surfing a song, you might notice the bumps, uphill climbs or downhill descents. Bumps are commonly found in Techno songs where the beat is always thumping. Uphill climbs mean that the section of the song is slow and downhill descents mean that the song is fast. You get an overview of the track before starting the song and it lets you know how crazy your song is. The more downhill descents, the faster the song and vice-versa. The game has a global scoreboard that keeps track of scores done in a song. The scoreboard is divided into three sections which are Easy, Medium and Elite. If you play a ship from the Medium section, your score will only appear in the Medium section. This also gives you a reason to be better because you'll be pumped with competitiveness just to get your score up that board.
There are many ships to choose from and they also determine the game mode. Mono ships (available in every level) are one of the basic ships that you'll probably use often. The objective of this ship is to dodge all the gray blocks and collect only colored ones. This is the only ship with this kind of objective. These ships also have power-ups like spreading it's wings to collect blaocks that are far from your reach. Pro Mono lets you jump over blocks and Ninja Mono lets you destroy gray blocks that have landed on your cluster. Destroying blocks decreases your score though so use it wisely.
Eraser ships (available in Medium and Elite) let you erase colors from your cluster. To make this work, you need to press the left mouse button and hit the desired color you want to disappear from your cluster. This ship is the easiest color cluster ship to use and it also racks the points up because of it's power-up.
Pointman ships let you pick up a block and use it later. To use it, you just need to hold the left mouse button to scoop up the block and right click to release it at the time you think that's best. This is probably the most complicated ship to use.
The Vegas ship (only available in Medium) is the funnest ship to use. This ship lets you shuffle up your cluster to hopefully make some color clusters. To activate this, you need to stay in the shoulder and wait for it to activate. This ship is pure fun and makes collecting all blocks needed to possibly score big points.
Pusher ships (available in Medium and Elite) let you push blocks to your left or to your right. To move the block to the left, just hold the left button mouse at a block and vice-versa. This ship requires a bit of strategy and is also tricky to use.
Double Vision ships (available in all levels) as the name implies, lets you play two ships, either with a friend or by yourself. This ship has no power-ups but is the most difficult to use alone. Unlike the other ships, this ship has four lanes instead of three making scores stack up like crazy.
Sound: This game lets you play any song that is available in your computer and CD. I'm rating it an infinity because of that.
Replay: With the tons of game modes, high score challenges and a playlist that is basically your whole computer, this game will keep you occupied for months and months to come.
Overall: One of the best rhythm-puzzle games out there. Get it ASAP. You will not regret it.