Challenge Type

There are four different types of challenges:

Rush

This is one of the standard challenge formats. You just need to establish your defenses and make survive until all enemy waves are repelled.

Survival

In this challenge, you'll have a timer, usually between 1 minute to 2:30 minutes. You need to survive the enemy assault until it runs out.

Max Towers

You'll have to defend your position with a limited number of towers. You must choose a chokepoint position and place your towers around it. You can upgrade the towers as necessary.

SOS

You won't gain any energy from enemy kills. The map you'll play will have pre-built towers so you can sell the ones you don't think you need and buy new ones/ upgrade existing towers using the starting energy you'll receive.