Helldivers 2 is set a century after the triumph of "Super Earth", a self-described managed democracy, over the Cyborgs, Terminids, and The Illuminate during the events of the first game. It is discovered that, upon death, the Terminids produce a unique and highly valuable resource E-710. Farms are established on human-colonized worlds, but containment is eventually breached, releasing the bugs and causing chaos and destruction. Simultaneously, a new threat emerges in the form of the Automatons, a mechanical army intent on destroying humanity.
Similar to the first game, players are able to select Stratagems, air drops players can call during missions, which include cluster bombs, sentry guns, shield generators or supply pods containing limited-use special weaponry. Friendly fire is always on. The game's armor system is inspired by real firearms fired against armored targets. The game features cooperative multiplayer with up to four players, but does not include a dedicated single-player campaign.