Serious Sam 4: Complete Guide

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.

Quick Start

• Never stop moving. Circle-strafe and backpedal. Standing still is how Sam dies. Most enemies are built to punish anyone who stays in one spot.
• You carry every weapon at once. Switch constantly: shotguns for close threats, the minigun for crowds, rockets and the cannon for big targets.
• Hunt S.A.M.s (Sirian Artefacts of Might). They buy skill tree points for dual-wielding, enemy riding and more. The "Get Serious" achievement asks for 10 in one playthrough.
• Do side quests. They award gadgets, weapons and upgrades that make the main campaign easier.
• Gadgets are panic buttons. Save them for moments when you're overwhelmed.
• Headless Kamikazes have priority. When you hear the scream, turn and shoot.
• Play co-op if you can. The campaign supports 4-player online co-op, and the chaos is the point.
• Pick difficulty honestly. Normal is a real challenge for newcomers; the Serious-style top end is for series veterans.

Story and Setting (Light Spoilers)

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.

Core Combat Rules

• Backpedal at an angle. Moving straight back lets fast enemies catch you. Diagonal strafing keeps them in front of you and chasing.
• Prioritize by threat, not size. Headless Kamikazes and Kleers close distance fastest. Big enemies are slow, so you can deal with them after the rushers.
• Use the terrain. Wide-open fields are Serious Sam's comfort zone. Tight spaces get you surrounded.
• Collect armor and health between waves. Don't leave pickups behind before a fight is truly over.
• Watch for spawn triggers. Big arenas often spawn more enemies behind you. Keep the camera turning.
• Legion battles: the Legion System fills late-game battlefields with thousands of enemies. Use high-damage area weapons and gadgets, and use vehicles when they're offered.

Enemies to Know

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

Weapons

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

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.

The S.A.M. Skill Tree

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:

• Dual-wielding any weapon. The "Quadruple the Gun" achievement asks for 20 kills while dual-wielding double shotguns.
• Enemy riding (mounting certain large enemies)
• Melee and utility skills, including using street signs as weapons

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 Worth Doing

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

Achievement Tips

The game has 54 achievements. Useful notes:

• Story ones (Regression, Ecclesiastical Extraction, All Roads Lead To Rome, See Carcassonne And Die, Class Reunion, The Last Human, Oil's Well That Ends Well, From Earth With Love, Serious Sam) come naturally.
• Skill ones: "No Surrender" (5 kills in a row below 10 HP), "Bullseye" (one-shot 3 Werebulls with a shotgun), "All Kleer" (50 healthy Kleers with a direct double shotgun hit), "Heads Up!" (100 headshots), "Dismemberfest" (50 cannonball dismemberments), "Spinal Tap" (melee 11 different enemy types), "Say Hello To My Mini Friend" (1,000 minigun rounds continuously).
• Volcano achievements: "Volcano Antagonizer" and "Hot Hot Hot" are tied to a HAARP-related sequence.
• "Oh, Shut Up": destroy 10 propaganda drones. Shoot them whenever you see them.
• "Get Serious": 10 S.A.M.s in one playthrough. Explore thoroughly in a single run.
• Co-op achievement: "Roman Holiday" asks you to "get together with your friends and kill something big."

Co-op Notes

• Up to 4 players online.
• Spread out when kiting so the horde splits, but regroup for bosses.
• Share pickups. Let whoever is lowest grab health and armor.
• Co-op supports modified difficulty settings for extra challenge.

Performance and PC Tips

• Steam Deck support arrived in a May 2022 update, along with performance, stability and new GPU support improvements.
• Legion scenes are heavy. If frame rate drops in large battles, lower shadow and crowd-related settings first.
• Mods: the Steam Workshop is full of community campaigns (see below).

Workshop Mods and What's Next

Croteam still highlights community work:

• Pyramid of Prophecy (featured September 2026) by Wolfen325 and Riba4ok13: an Egypt-themed campaign with huge encounters, secrets and hidden bosses, with no SS4 gadgets.
• Serious Sam Reborn (featured February 2024) by Nonamewtff: a 10-level, 5 to 6 hour campaign with new and returning weapons.

Related releases:

• Serious Sam: Siberian Mayhem (January 2022) is a standalone expansion built on SS4.
• Serious Sam: Shatterverse (31 August 2026, by Behaviour Interactive) is a co-op roguelite spin-off for up to 4 players.

Common Mistakes to Avoid

• Fighting in corridors. Pull hordes into open spaces.
• Hoarding gadgets forever. They exist to get you out of trouble. Use them.
• Ignoring side quests. You'll miss S.A.M.s, weapons and gadgets that make later fights easier.
• Using one weapon for everything. Match the gun to the target and conserve heavy ammo for heavy threats.
• Running straight backwards. Strafe diagonally.
• Skipping armor pickups between waves.

Advanced Tips

• Dual-wield double shotguns for the best close-range burst in the game.
• Cannonballs pierce through lines of enemies. Line up crowds before firing.
• Belcher barf hurts other enemies. Position a Belcher behind a crowd you're kiting.
• Psychotropic Grenades in mixed crowds do more work than any gun.
• Explore for S.A.M.s early so your skill tree is strong for the Legion battles.
• Replay levels on higher difficulty in co-op for the full Serious experience.

FAQ

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.

Sources

• Steam store page: Serious Sam 4
• Wikipedia: Serious Sam 4
• Steam global achievements: Serious Sam 4
• Steam news: Featured Mod, Pyramid of Prophecy
• Steam news: Serious Sam Shatterverse out now
• Steam news: Serious Sam 4 now supports Steam Deck
• Steam news: Featured Mod, Serious Sam Reborn