Your base is under attack by enemy soldiers so you have to take them out! Shoot them all to clear an area. You can buy new weapons with the money you earned after each day. Can you hold down the fort until all 19 days have passed?
Aim and click to fire, switch between weapons with mouse or with number keys 1, 2, 3, 4.
Source
http://flonga.com/play/incoming-again.htm
Incoming Again screenshots
