This covers Serious Sam 4 for solo and co-op: horde-fighting fundamentals, the arsenal and gadgets, the S.A.M. skill tree, side quests worth doing, achievement pointers, and the Workshop mods and spin-offs that keep it alive in 2026.
Researched September 2026, current as of the final Steam build (last content/performance update: Steam Deck support, May 2022); Workshop campaigns are still being featured by Croteam. Live games change; check the linked sources if something differs.
Serious Sam 4 is a prequel set before Serious Sam 3: BFE. Mental's invasion is overwhelming Earth, and the Earth Defense Force, led by Sam "Serious" Stone and his squad, goes after a relic that could turn the war: the Holy Grail. The invasion's bridgehead is a huge portal in Tunguska, Russia, and the campaign moves through Rome, the Vatican, Pompeii, the French countryside, the citadel of Carcassonne and an Arctic oil rig. Main villains include General Brand, Mental's general Lord Achriman, and the giant Ugh-Zan VI.
Named allies and side-quest characters you'll meet include Father Mikhail, Massimo Murena, Rodriguez, Gabriella, Dr. Stein, Professor Kiesel, Dr. Vermetti, Secchi and Fulbert.
| Enemy | Threat | How to handle |
|---|---|---|
| Headless Kamikaze | Screaming suicide bomber | Kill at range. Any weapon works; don't let them reach you |
| Beheaded Rocketeer | Ranged rockets | Strafe sideways; low HP |
| Kleer | Fast skeletal charger | Double shotgun at point-blank; there's an achievement for this |
| Werebull | Charging bull | Sidestep the charge and hit it with the shotgun or cannon |
| Scrapjack | Heavy rocket-launching brute | Keep distance; rockets or the cannon |
| Khnum | Big hard-hitting enemy | Heavy weapons, keep moving |
| Processed | Frantic new infantry type | Crowd weapons like the minigun |
| Belcher | Repulsive ranged enemy with barf attack | Its barf can damage other enemies (see the "Megabarf" achievement) |
| Zealot | Hard-hitting new enemy | Burst damage from range |
| Witchbride | Caster-type | Focus down fast; explosives work |
| Aludran Reptiloid | Ranged reptile | Even a pistol can kill one, as the "Pow Pow!" achievement shows |
You carry the whole arsenal. The weapons below come from Croteam's store description and the achievement list:
| Weapon | Best for |
|---|---|
| Pistol | Infinite-ammo backup and precise shots |
| Double-barreled shotgun | Point-blank burst; the signature Serious Sam gun |
| Auto shotgun (new in SS4) | Sustained close-range damage |
| Minigun | Shredding crowds; watch ammo |
| Grenade launcher | Area damage on groups |
| Sniper rifle | Headshots on high-value targets at range |
| Rocket launcher (with lock-on) | Big enemies and groups |
| Chainsaw launcher | Slices through lines of enemies |
| Cannon | Huge single shots; dismembers enemies |
| Laser | Continuous high damage |
Weapon mods unlock alternate fire modes. They're found through exploration and side quests, and are well worth hunting.
Gadgets are single-use tools picked up in levels. Gadgets confirmed by the achievement list:
| Gadget | Effect | Use |
|---|---|---|
| Time Warp | Slows time | Clean up a surrounding horde; "Max Pain" is for 5 kills in one warp |
| Psychotropic Grenade | Makes enemies fight each other | Throw into a mixed crowd |
| Black hole (weaponized) | Sucks in enemies | Huge crowds; one side quest rewards it ("Hard Science Fiction") |
| Mini-nuke | Massive explosion | Legion battles; "Atomic Wedgie" asks for 100 kills with one |
| C4 | Placed explosive | Big single targets; "Veni Vidi Witchy" is for a Witchbride kill |
Gadgets are also available as support items that give buffs. Use the gadget wheel early in a crisis, not when you're already at 5 HP.
Sirian Artefacts of Might (S.A.M.s) are hidden or earned throughout the campaign. Each one gives a skill point, and there are only 10 per playthrough, so "Get Serious" means finding every one. The tree includes:
Priority for most players: dual-wielding first (it roughly doubles your output with your favorite weapons), then mobility and survival skills. Look for S.A.M.s off the main path, especially in side quests.
Side quests are optional objectives that reward items, weapons and gadgets. The achievement list points to several. Each line below is the achievement's own description:
| Achievement | Hint |
|---|---|
| Cultist Stimulator | Recover a key stolen by a cultist |
| That Belongs In A Museum | Recover the alien artifact located by Dr. Stein |
| For the Cause | Find out what happened to Alessandro |
| That Burning Sensation | Collect scorched aliens for Professor Kiesel |
| Hard Science Fiction | Get a weaponized black hole, using science |
| La Nonna é Mobile | Meet a powerful granny |
| Holy Driver | Ride the Popemobile to victory |
| You Have Been Wormed | Assist Dr. Vermetti in his war on worms |
| Signature Move | Sign Secchi's rifle |
| Serious Art | Protect humanity's treasures from invaders with no taste |
| Classic Hero Stuff | Save a princess |
| Brass Lantern | Finish a text adventure on an oil rig |
| Harvest Festival | Harvest 100 enemies with a combine harvester |
| Southern Gentleman | Assist a couple of young ladies out hunting |
| Fulbert le Fou | Discover Fulbert's great invention |
| Mushroom Surprise | Find out what happened to the English airman |
The game has 54 achievements. Useful notes:
Croteam still highlights community work:
Related releases:
Is Serious Sam 4 multiplayer? Yes, 4-player online co-op across the campaign.
Do I need to play earlier games first? No. SS4 is a prequel and stands on its own.
What is a S.A.M.? A Sirian Artefact of Might, which unlocks skill tree abilities like dual-wielding.
Is Siberian Mayhem required? No. It's a standalone expansion with its own campaign.
Does it run on Steam Deck? Croteam added Steam Deck support in May 2022.
Is there a new Serious Sam? Serious Sam: Shatterverse, a co-op roguelite, launched on Steam on 31 August 2026.