Alien Murderers

The aliens attacked suddenly. The bombing of the cities lasted several months. There are no living on the surface. In underground laboratories, scientists have almost developed new weapons to destroy alien spaceships. But the aliens began a ground operation. The invaders by the way get people out of the basements and kill. Your command decided to allow special forces to rise from underground shelters and detain the aliens. With all the special groups, only you survived. Kill aliens, give scientists time to complete the development of weapons.