Notepad invaders

This interpretation of Space Invaders, but now the whole game is made on the notebook sheet. As before, you will attack the alien invaders that attack close formation. Shots from the enemy can hide behind a brick barrier, but they are gradually destroyed. Build gradually descends, we can not allow them to get to the ground. You have three lives that will take for getting your ship. At each new level will be a new system invaders, new ships and danger.