You can play the game offline with 1-4 local players. However when played offline, mission progress will not contribute to the global galactic campaign.

Does Helldivers have a campaign?

By playing Helldivers, every player in the world participates in a global meta campaign called the Galactic Campaign. Each time a player conquers a planet, the Influence they gained is uploaded and their contribution to the Galactic Campaign registered.

Can you play Helldivers online?

Helldivers offers 1 – 4 players, local and online co-op multiplayer for both PC and PlayStation. You can also play the game offline with 1-4 local players, however when played offline, mission progress will not contribute to the global Galactic Campaign.