Abort: timeout or 'a' key,
Move: mouse or cursor keys,
Erase: middle mouse button or 'e' key,
Rotate: right mouse button or return key,
Drop: left mouse button or space key or automatic,
Press left mouse button or any other key to play
You have to drop the blue piece within the time indicated by the yellow bar, i.e. four seconds.
After that time, the game tries to drop the piece automatically.
If you build a closed loop it will dissolve into score, one point for each tile of the loop.
If you clear the whole field, your points will be doubled.
Erasing can only be done if the blue piece coincides with the underlying tiles and only if you scored at least 100 points since the last erasing was done, which is indicated by an 'X'.