In every game it appears in, napalm is an orange tank with a mask logo and some attachment pipes on it.
The amount of napalm depends on the game it is in. On Normal, Hard and Mental, Serious Sam: The Second Encounter and Serious Sam HD, it gives the player 50 Napalm units when picked up, while on Tourist, Easy and Serious it gives the player 100 napalm per pickup. Serious Sam: Next Encounter napalm gives 100 per pickup, while Serious Sam: Double D's napalm pickup gives 50 napalm.
Serious Sam: Next Encounter contains two napalm variants: nitrogen and laughing gas. Nitrogen makes the XOP Gas Gun behave the same as normal napalm does, but instead freezes the enemy when it is killed. Laughing gas will stun enemies by making them laugh, letting the player continue hitting them with laughing gas or kill the enemy with another weapon.
- Napalm is quite common in Serious Sam: The Second Encounter and Serious Sam HD, which lets the player use the XOP Flamethrower often.
- Laughing gas is quite rare, and is usually found only in secrets.