Earth Defense Force: Insect Armageddon has a campaign mode and a campaign remix mode. Choose the latter option and you can replay stages with different waves of enemies.
You might see spiders instead of ants or giant ticks, enemies that latch on to players until you mash Y to make them explode, appear in other stages. Basically, campaign remix randomizes enemy waves to give players a slightly different challenge.
Developer Vicious Cycle also added a survivor mode where you face endless waves of giant bugs and Hectors until your platoon is killed off. In survivor mode you can only play as the trooper. Jetpack armor and tactical troops from campaign mode are out. You can still equip your ant exterminating soldier before you head to the battlefield. The level I played had one tank for the group to share. The tank doesn’t recover either so if it gets destroyed in wave two, it’s gone forever. I tried "tank surfing" for a bit by firing rockets while standing on top of the tank. Not really an effective strategy, but it was fun to try.
Every few levels, health packs will pop up inside a base so there is a chance to restore life. However, survivor is a fight to the death. Eventually, the bugs will win. The challenge is to see how long you can last.
Earth Defense Force: Insect Armageddon is scheduled for release on July 5 for PlayStation 3 and Xbox 360.