Do you think that a science fiction themed game that is a combination of a tower defense and a card game sound like fun? If so, Android owners can head on over to Google Play and pick up Tau Ceti, which was just released for Android devices. It's free, go for it.
In this tower defense game you will be attempting to protect your orbital station using anti-gravity, weapon and technology combat cards. You will also be able to take advantage of asteroid fields and other space environment stuff to assist in the defense.
Since it's free, you may as well check out Tau Ceti on Google Play.