Electro is a falling blocks game. You should make a connection from one side of the screen to the other with the same type blocks. You can downgrade once a selected cube with down or B key (blue triangle become green circle, red square become blue triangle ...). Make combo (multiplicate points) with followed lines.
Two modes are available. In puzzle game, you should move cubes vertically. New lines appears automatically at the bottom of puzzle but you can add them with L or R key.
Enjoy it !
More informations and dowloads on my blog (in french).