In the Underground Invasion flash shooting game you are on a mission to defend your base and your underground city against the creeps who are advancing and trying to take you down. Underground Invasion is a fun shooting video game that also has you using defense strategies as well. The sewer creatures in Underground Invasion are trying to escape the sewer and make their way out into society so its up to you to use all of your different guns and weapons to kill them before they escape. Your mission in Underground Invasion is simple. Kill as many creatures and earn money which you can spend on upgrades for improving your defenses, turrets and weapons.
