Serious difficulty is recommended only for the most serious, experienced players. On the other hand, I Am Ugh-Zan difficulty, only available in Serious Sam Classics: Revolution, is essentially Serious difficulty but with 50% extra enemy health and the chance that enemies will spawn with fire or ice modifiers that can gradually harm or slow down the player, respectively, upon contact with them. By comparison, Mental difficulty, despite being the last possible difficulty in some games, only offers the same amount of enemies and enemy strengths featured on Hard difficulty. Serious difficulty can be considered the greatest challenge in a Serious Sam game, as it offers the highest caliber of enemies featured in any difficulty.

Only in certain games is Serious difficulty the highest, and final difficulty setting. Serious difficulty is generally the penultimate difficulty in most of the Serious Sam games, as Mental difficulty (I am Ugh-Zan difficulty in the case of Serious Sam Classics: Revolution) is usually featured as the last possible difficulty.

Finishing Serious Sam 1, Serious Sam HD, Serious Sam 3: BFE, Serious Sam VR, Serious Sam 3 VR: BFE and Serious Sam 4 on Serious difficulty unlocks Mental difficulty, and finishing the difficulty in Serious Sam Classics: Revolution unlocks I Am Ugh-Zan difficulty. It is featured in almost all Serious Sam titles. Serious difficulty is a difficulty setting in the Serious Sam games.

Serious sam 3 difficulty