Onslaught is a free roam sandbox game mode which the player must kill the enemies and buy new areas which will unlock new, weapons, vehicles, powers, traps, enhancements and weapon upgrades.
Most of the time the Devourers will swarm the player but the deadly experients, the Exomens, will appear. No-one knows why the Exomens have appeared but no-one wants to find out...
| Onslaught Campaign
The Announcer is an unseen character but he somehow knows what is happening. He will announce special features and actions within the Onslaught.