
Enemy units that come in contact with the player(s) will try to raise an alarm, which will result in continuous waves of enemy reinforcements for as long as the alarm remains active.

The enemy will patrol their territory, impeding the player's attempt to complete the given objectives. The game keeps many of the mechanics common to the genre, like Fog of War and a map that shows any enemies the player(s) can currently see. It often benefits the player to avoid direct combat if possible, as the enemy has infinite reinforcements, and there are no in-game rewards for simply killing enemies.

It is possible to fail some of the given objectives without immediately losing.

In each mission, the player must fight or sneak through enemy-controlled territory to complete the given objectives, then escape via a dropship. This had changed over the course of development. The game features a single difficulty option, though the player can then choose a hard or easy planet for their missions. For example, the player may choose stratagems that focus on providing additional firepower or mobility, or give themselves supportive abilities like calling in an airstrike on parts of the map. At the start of each mission, the player can choose their loadouts and deployment positions, as well as using the game's unique stratagem mechanic to assist additional options to best suit the map or the player's preferred playstyle. Gameplay takes place on procedurally-generated missions where players must accomplish a series of objectives. The game pits the player against three different enemy species and tasks them with ensuring the survival of Super Earth. In Helldivers, the player needs to coordinate their actions during chaotic combat in order to complete objectives and to avoid friendly-fire casualties. A sequel, Helldivers 2, was announced in May 2023. This comes with its own risks, however, most notably friendly fire. While solo play is possible, it is often beneficial to play cooperatively, as this allows the players distribute the requirements effectively. Helldivers takes inspiration from military science fiction such as Aliens and Starship Troopers. It features both couch and online co-op, up to four players. A version for Microsoft Windows was also released via Steam on December 7, 2015, making it the first game Sony released on PC.

The game was released for the PlayStation 3, PlayStation 4 and PlayStation Vita with cross-play, on Main North America and on Main Europe, respectively. Helldivers is a top-down shooter game developed by Arrowhead Game Studios and published by Sony Computer Entertainment.
