The Cryo Grenade is a Grenade in SAS: Zombie Assault 3, SAS Zombie Assault Tower Defense, and SAS: Zombie Assault 4. When thrown, it explodes and freezes all zombies in its radius, dealing minor damage. Originally in the PC version the player could only obtain them for free by picking up Power-up crates, but an update was added that the player now started with 6 (and could still find them in Power-up crates).
These can be quite useful against Devastators, as being immobilized, the player can fire off many shots without having to worry about being hit by the ground-pound attack/punches.
In SAS 4, the cyro grenade's freeze duration is much shorter and it only slows down bosses.
- Despite cryo grenades not existing in reality, they are stated to use the liquid form of molecular oxygen. Molecular oxygen is found pretty much everywhere in its gaseous form, but it has a very low boiling point, therefore the liquid form is extremely dangerous, as it can not only turn you into a popsicle, but it can also cause frostbite, which can be fatal.
- In SAS3 and SASTD, cryo grenades are shown to use ordinary molecular oxygen (O2). However, SAS4's cryo grenades use oxozone (O4).
- In SAS4, all regular zombies will be gibbed if they die in the Cyro Grenade explosion or killed while frozen (not including bosses), except when killed by any DoT Weapon, which will result in death animation of the damage type instead.
- In SAS4, cryo grenades have a max pierce of 10, whereas in SAS3 it is unlimited to the zombies within the explosion radius.
- It is advisable to save Cryo grenades for tight spots or Devastators.
- Mamushka and burrowers become easier to kill since they rely on heavy numbers and when frozen they're nearly helpless.
- In the PC version of Zombie Assault 3, Cryo grenades encase the zombies they hit in ice. In the mobile version, it merely turns them blue. Notably, the Devastator will sometimes have a blue sphere appear seemingly on top of it. This appears to be due to that the Devastator is slipping an attack through (despite being frozen), as a circular shockwave/dust cloud appears around the Devastator when it pounds the ground to attack or summon skeletons. This likely means that the game is counting this shockwave/dust cloud as part of the Devastator when it does this (and thus turns it blue as well).