Here's a set of Serious Sam 3: BFE screenshots that show the weapons in Croteam's shooter prequel, all of which can be carried at once, oldskool style.

Sledgehammer
The sledgehammer can be swung from an overhead position for maximum damage or from the side for quickly clearing enemies directly in front. An alternative fire allows the sledgehammer to be swung a full 360 degrees to clear out anything in the surrounding area. Watch your toes.

SOP38 Semiautomatic Pistol
A special issue pistol that has proven its combat effectiveness on numerous battlefields across the universe. This small gem can unload a burst of damage into an opponent, but its small magazine capacity precludes its use in massive fights.

12 Gauge Pump Action Shotgun
Ordinary slug pellets are efficient for short and middle range elimination of smaller enemies. Standard 10-shell cartridge allows for faster reloading and faster overall average rate of fire.

Double Barrel Coach Gun
A standard civilian double-barreled 12 Gauge shotgun originally marketed for hunting and self-defense, it has proven to be very effective against most aliens.
Efficient for short-range elimination of medium sized enemies, but scatters the pellets too much to be used for long range shooting.

M29 Infantry Assault Rifle
The M29 is best described as a hybrid of previous rifle technology innovations with a gas operated, rotating bolt mechanism for rapid-fire mode and controlled short bursts. The reflex sight allows for quick target acquisition and easy tracking. At 600 rounds per minute, with long range and low dispersion, it is well suited for most combat situations.

XM214-A Minigun
Evolving from Gatling through Vulcan and M134, XM214-A is latest news in infantry armament. Self-powered and complete with a built-in magazine and a recoil adapter, this is the most powerful personal weapon available. At 1200 rounds per minute, it is ideal for confrontation with tough enemies or mass elimination of a large number of smaller opponents.

XPML21 Rocket Launcher
Experimental personal missile launcher XPML21 is designed to provide infantry forces with a fast firing rate of anti-armor rockets. Advanced loading mechanism fires up to 85 unguided self-propelled missiles per minute. Do not fire near close obstacles.

AS-24 Devastator
Referred to informally as the "Devastator" on the battlefield, this automatic shotgun fires explosive shells with such force that the rounds pierce through smaller targets and shred enemies standing in line. Brings the boom all day.

SBC Cannon
The cannon was reverse-engineered from powerful techno-magical weapons used by Mental’s artillery. Cannonballs can be fired in rapid succession and the weapon can be charged to release an incredibly destructive flaming cannonball.

C-4 Demolition Charge
C4 charges can be used to blow holes in architectural obstacles, to eliminate groups of smaller enemies or to attack larger individuals. The remote control unit is used to detonate one or more charges simultaneously from a safe distance. Using the hooks, skilled throwers can attach a charge to an enemy without approaching too closely.

XL2 Lasergun
The XL2 is still in experimental phase, but has so far proven to be a very reliable weapon for various purposes. The four barrels fire in succession, allowing the weapon to deliver energy pulses with extremely high rate of fire for a long period of time without overheating. Made entirely of titanium, it is both very light and immune to usual overheating problems making it an excellent energy weapon.

RAPTOR 16mm Sniper Rifle
The 16mm armor-piercing, Kevlar coated bullets will pass right through most known armor types. A Flexible 2x-4x zoom ratio allows the shooter to choose between a larger peripheral field of view and more precise aim at longer distances.

Sirian Mutilator Bracelet
Ancient artifact of presumably Sirian origin. The inscription reads "He shall devour the nations of his enemies, break their bones, and with his arrow shall tear them in pieces." This display appears to indicate when the weapon is charged enough to deliver damage to the target. Apparently, this item also doubles as a key to some restricted areas of Sirian underground complexes.