DefenseDoodle

*Original*
Draw blockades to protect your space stations from invaders.  Erase the blockades when they're no longer needed, so you can draw them where new space stations need protection.  But be aware, you only have a limited amount of ink, so you have to be smart, and quick about where you draw, and erase your blockades.

NOTE: If you like this game, there is an enhanced version, with no adverts, enhanced graphics, and plays full screen on all devices, including tablets.  The enhanced version is called DefenseDoodleX.  (Just search for it in the app store search bar)