Undead Storm is an action game that, as is probably obvious, is about zombies. Following the Left 4 Dead school of zombie gaming, Undead Storm features four available survivors for players to choose from (all of whom play identically) as they blast away at undead hordes. All four characters appear in the stage together and fight as a team. Often, the AI-controlled characters start out injured somewhere in the level, requiring the player(s) to find them and revive them.
The game is played from a slightly-angled top-down view, and operates much like a typical Twin-Stick shooter, with the exception that players manually turn their character with the L or R buttons, and attacks are assigned to different buttons, with a pistol, a special weapon, and a throwable weapon, such as a grenade.
Unlike the aforementioned Left 4 Dead, however, players aren't trying to reach safety. Instead, players merely shoot it out in one of three stages with five waves of zombies each. There are also a few specialized zombies that mostly appear in the form of three different boss characters.
Players have a variety of weapons at their disposal, from the ever-classic shotgun, to a better pistol (the default has infinite ammo), and even a flamethrower and Molotov cocktails. These appears as drops from enemies, along with the occasional health, which when used, affects the team as a whole.
There are also 80 achievements to unlock over the course of the game, and three difficulty levels. "Completing" the game (where a player sees end credits) occurs after playing through all three stages in one sitting with a single character.