Serious Sam 4: Sidequest Locations and Rewards

Thanks to Mauritsio for providing this list:

Death from Above

• Over the Wall – Holodecoy

Death from Below

• We can be Heroes – Assault Rifle

Four Horsemen of the Apocalypse

• Key to Success – Rage Serum
• Thin Red Line – Shotgun Grenade Launcher Attachment
• Amateur Archeology – Time Warp

Gates of Hell

• Collect Samples – Multirocket Attachment

The Die is Cast

• Portal Kombat – Black Hole

Morituri te Salutant

• Cоcked, Locked and Handcocked – Mininuke

When in Rome

• Gabriella’s Knight – Rage Serum
• Worm’s Armageddon – Psychotropic Grenade

Machina Ex Deus

• There are no sidequests for this level

A Breakfast in France

• A Fun Guy – Rage Serum
• Southern Belle Tower – Sniper Rifle
• Droning On – Hacked Drone

One for the Road

• Armed, Farmed and Alarmed – FRPCL
• La Route de L’enfer – H.E.A.R.T.

Vive la Resistance

• The Art of War – Autoshotgun
• Let’s Workshop This – Holodecoy

In Carcassone

• The Princess and the Pie – Master Key
• Portal Too – Black Hole

Anathema Unto God

• Lock and Key – Time Warp
• What the Hellfire – Mininuke

The Package

• Twisted Little Passages – H.E.A.R.T.

From Earth with Love

• Canyon Fodder – Rage Serum

Over the Wall
You can’t miss this one as Kenny will initiate it.
Reward: Holodecoy x2

We can be Heroes
Again, can’t miss this one as Father Mikhail will initiate it
Reward: Assault Rifle

Key to Success
Right after you leave the first arena, you will come across a locked door. Interact with it to activate the side quest.
Reward: Rage Serum x3

Thin Red Line
In the shack next to the radio, there will be a note. Interact with it to activate the side quest.
Reward: Shotgun Grenade Launcher Upgrade

Amateur Archeology
Progress through the level normally and Dr. Kiesel will contact you, activating this side quest.
Reward: Time Warp x2

Collect Samples
Once again, progress normally and Dr. Kiesel will contact you for this side quest.
Reward: Multirocket Attachment

Portal Kombat
Hard to miss, it’s just before the Grenade Launcher attachment.
Reward: Black Hole x3

Cоcked Locked and Handcocked
Before the big arena with a bunch of Processed and Scrapjacks, to the right there is a blockade with an NPC. Interact with him to activate the quest.
Reward: Mini Nuke

Gabriella’s Knight
The side quests on this mission are pretty obvious, the first is right after you leave the canal area.
Reward: Rage Serum x3

Worm’s Armageddon
The second sidequest is after the bridge fight. Again, hard to miss.
Reward: Psychotropic Grenade x3

A Fun Guy
This one is actually easy to miss, because all the previous ones were kind of obvious. When you get the bike, there are some small ruins to the side, and an audio log. Listen to the log to activate the side quest.
Reward: Rage Serum x3

Southern Belle Tower
After getting the bike and driving down the main road, you’ll come across an abandoned house. From the house you will see a tower in the distance. You should get a call from Anabelle while driving towards the main objective, but if you don’t, simply head to the tower (shown in the screenshot) and you’ll get the side quest.
Reward: Sniper Rifle

Droning On
This one is also easy to miss; After the combine harvester segment, before the exit, you can see a radio tower off in the distance. Go there to activate the side quest
Reward: Hacked Drone x4

Armed, Farmed and Alarmed
After the mech segment, you’ll come across these large containers and a small white shack to the right. Read the note inside the shack to activate the side quest
Reward: FRPCL

La Route de L’enfer
After getting the quad bike, keep driving towards the main objective and you’ll get a distress call. If you don’t get it, simply drive towards the large smoke trail in the distance.
Reward: H.E.A.R.T. x1

The Art of War
Progress normally through the canal with Michelle and Sayid until you reach this split and take a left, under the bridge
Reward: Autoshotgun

Let’s Workshop This
Again, progress normally and Michelle will mention there’s an abandoned workshop nearby.
Reward: Sadly, not a resors, just a Holodecoy

The Princess and The Pie
This side quest even has a cutscene, you cannot possibly miss it
Reward: Master Key (unlocks some rooms with extra ammo)

Portal Too
After the arena where you first get the Lasergun, you’ll see the side quest marker on your right, and then a long walk to quite possibly the most difficult side quest in the game
Reward: Black Hole x3

Lock and Key
Before going through this locked gate, on the shack to the right is another small piece of paper. Interact with it to trigger the side quest.
Reward: Time Warp x2

What the Hellfire
Right after Hellfire’s cutscene just go right.
Reward: Mini Nuke x1

Twisted Little Passages
Again, hard to miss this one. It’s just after going back inside the oil rig interior for the second time.
Reward: H.E.A.R.T.

Canyon Fodder
From the starting area, go right and you’ll see a small opening in the cliffs with a side quest marker.
Reward: Rage Serum