The colonists are under attack! Construct towers with gun turrets to defend the colonies from the brutal alien attacks. Research better habitats, mining facilities and weapons to give your civiliazation the advantage. The game's construction system is block based, making it fresh and easy to manage. The vertical tower defence style seems to work out very well.
Select the a block from the bottom panel and place it using your left mouse. You can research more block types and arange the construction bar in the menu between each battle.