Space Base Defence

The human mankind has colonized space with several bases on the planets of the moon, mars and venus. Today an unknown special has entered our solar system. An inexorable race of robot bugs, with hostile intentions. You are our last hope to lead human mankind to survival, by building defence towers, and improve our technology. Our scientists developed special weapon ion canon. You can use it by mouse click or press 1 on keyboard. You can upgrade it after each level. But now, stop them. Protect colony from invaders. Each dead bug gives you experience points. Your progress automaticly saved before and after each level. Try to play easy levels several times to earn more experience.