Reset the Galactic Campaign

There is not proper way to manually reset the Galactic Campaign, as it was not intended to be played this way. However if you really want to disconnect yourself from the current Galactic Campaign and play with all races there are a couple of things you can do.

Steam

Things to know:

• this only works for offline play
• local co-op works like normal
• you need to keep your internet connection disabled/unplugged while playing
• this also resets all of your progress
• make sure you back up all your saves before trying anything out
• you will have to play through the intro and tutorial again

1. Delete or rename your save games:

Go to %appdata%\Arrowhead\Helldivers and rename your saves folder to saves-backup (if you want to restore where you left off (just rename it back).

2. Delete or rename your cloud saves:

If you have Steam cloud-saving enabled, you also need to remove your saves from your main Steam install location (by default it's in C:\Program Files\Steam).

Go to C:\Program Files\Steam\userdata\<user id>\394510. Move all those files into a backup folder somewhere else or delete them. They'll update from your local saves later on if cloud-saving is enabled.

The <user id> is your Steam id, and you probably just have one folder to choose from. If not, use Steam ID Finder to get the right one. Go to your Steam profile page, copy that URL and paste it into the search. The folder will be the last number in steamID3 e.g. in [U:1:1234567], it's the 1234567 part.

3. Prevent it from connecting online:

You will need to be completely offline to prevent connecting to the campaign. Unplug your ethernet cable, turn off wifi, or disable your network from your control panel.

Alternatively, you can add some firewall rules to prevent just Helldivers connecting. If you ever accidentally run the game while online it will join the galactic campaign again. It will try to update the campaign after each mission but it'll just show connection errors.

4. Backup your save games to prevent unhappy accidents

Each time you play Helldivers (just before you launch it), backup your save games in the %appdata% folder. Just copy the folder somewhere. If you accidentally play online, just replace that folder with your backup. You'll also need to clear out your cloud saves again.

PlayStation

You need to play (and stay) offline and any save data should first be backed up before completing any of the below steps.

PS Vita - This is not possible on Vita.

PS3 - You need to play offline, and you can delete just the general save (which contains the Galactic Campaign info). This will force you to complete the intro and tutorial the next time you start the game. There should be another save file that holds your progress, so you will retain all of that. 

PS4 - Unlike on the PS3, on PS4 you can't delete just the general save, you would have to delete all data - including your personal progress. You need to play offline once you have deleted your save, and if you go online at anytime, PSN will pull all your save data back from the cloud, updating you to the current GC status again.