Massivematch is essentially the classic match 3 or more genre taken to an online environment and put to a much larger scale, some may say massive ;). You'll start immediately in a game with a screen full of animals/shapes to match in order to get points and combos, in the same game will be a ton of other players who all affect the board with their moves so you'll need to be fast with yours!.
If like me your eye sight isn't the greatest for small images I'd recommend playing near the bottom of the screen as the higher you are up the more shapes fall/move when people match squares. By being near the bottom you're pretty much guaranteed to not run into this issue and you'll be able to work at your own pace. There is a time limit to each of the matches but another will begin soon after one ends, once the round is over your performance will be ranked from 1-x depending on how many people are on the server so you can see how you fair against other people.
Your job is to match 3 tiles, to do so simply click and drag a tile that needs to be moved for another(must be touching).
You can also move around by dragging with the right mouse button or using the Arrow Keys. Mouse wheel can be used to zoom in and out to give you a bigger view of the action.