Insane survivors are the few to survive the carnage on Isla Salvaje, albeit at the cost of their mental status. They resemble any ordinary person, though they move spastically and mumble loudly to themselves. They can be found wandering all the areas on Isla Salvaje—except for the cavern, fort, and canopy areas—hunting down and attacking anything that moves, even each other. They are no friends to Ecsyth and his minions, though they don't often attack each other—the crazed survivors being too frightened to go up against the powerful undead, and Ecsyth seeing them as useful tools. Still, some will often gather the courage to go up against the skeletal monstrosities, but rarely manage to defeat them. As a result, most take to attacking the island's town to get at the British soldiers and sane survivors inside, but haven't been able to successfully penetrate their defenses.
Having lost their grip on reality, the unstable survivors will attack anything and anyone on sight. Their sense of pain has also been numbed greatly, making stun and flinch attacks ineffective. In addition, insane survivors are diverse in level (ranging from level 35 to 50), appearance (wearing ragged or fancy clothing), and weapon choice (resorting to blades, guns, and even their own hands).
The survivors drop a variety of loot, ranging from items as crude as a rusty cutlass to the legendary World Eater Blade, the cursed blades being dropped as a result of Isla Salvaje's current state.
The insane survivors have multiple different versions, wielding a variety of weapons to take down their victims. Though all the variants are simply labeled "Insane survivor", players assign them different titles after their preferred form of fighting.
The swordsman variant—as its name suggests—carries around a sword as its primary weapon; that weapon, whatever the model is, will be dropped upon defeat and be included in the loot container. The attacks also vary depending on level; lower leveled swordsmen are more clumsy with their moves, whereas the higher leveled ones will be more fluid. Most insane swordsmen come in the form of Black Guard soldiers, whose moves are more precise than the regular ones.
The marksmen patrol the war-torn island, wielding pistols or muskets with bayonets. They wield their firearms with great precision and use poison shots, making them very dangerous at a distance. Their bayonets are poisoned as well, making them formidable opponents in close combat. Their melee and shooting abilities are just the same as any other player's.
Scratchers carry no weaponry whatsoever, instead relying on hand-to-hand combat, biting, and scratching. Scratchers aren't much of a threat from afar, but their speed allows them to dash over to a player quickly and deal surprisingly large amounts of damage. Their main forms of attack are biting victims in the throat and arm areas or clawing at them with their fingernails.