This Game Lets You Bolt a Machine Gun to a Shotgun, top it with a Chainsaw and Add Another Machine Gun

In Serious Sam: Double D, you will beat a hasty retreat as scores of giant, headless Amazonian women carrying lit cartoon-style bombs over their naughty bits chase you.

You'll also probably curse at the screen more than a few times as hordes of animate pancake stacks stuffed with ringing vuvuzelas charge you with their explosive kamikaze attack. The few things you meet in the game that don't explode will still find their own ways to kill you.

Good thing you can come to this party armed with four stitched-together chainsaws.

This Game Lets You Bolt a Machine Gun to a Shotgun, top it with a Chainsaw and Add Another Machine Gun

To be fair, the whole quad-chainsaw thing isn't really a possibility until later in the game. The weapon-stacking though, which is unlocked early on in the first chapter, is at the heart of what makes Double D's side-scrolling dual-stick gameplay so entertaining. I played a handful of levels from an alpha build of the game and had a great time with that feature. This is an upcoming PC and Xbox Live Arcade side-scrolling shooter worth paying attention to.

It's no surprise that this charmingly loony shoot 'em up is the work of Mommy's Best Games, developer of the Xbox Live Indie Games release Weapon of Choice. The large levels are marked by multiple paths and tons of hidden goodies, just like the earlier game. And while many of the beasties Sam faces are pulled from the Serious Sam rogues' gallery, others are off-the-wall creations that will make you stop and stare at first sight. You did read the bit about vuvuzela-stuffed, exploding pancake stacks, right?

Double D can be played using a mouse and keyboard, but the controls are better suited to a twin-stick gamepad of some kind. The mouse might offer a bit more accuracy, but there's no replacing that right stick for aiming quickly in 360 degrees. The PC version of the game even recognizes an Xbox 360 controller right away, replacing keyboard prompts with the appropriate button icons in tutorial pop-ups.

Back to the Gun Stacker: it works as advertised. Sam collects a wide variety of weapons, including multiple duplicates, over the course of his side-scrolling journey. Up to six of them can be combined into a single "stack," and up to eight stacks can be stored to suit different situations. The grenade launcher, for example, runs out of ammo quickly and is very dangerous to Sam at close range. You'll want to save that for the game's assortment of giant bosses.

This Game Lets You Bolt a Machine Gun to a Shotgun, top it with a Chainsaw and Add Another Machine Gun

It's hard to capture in words just how delightful it is to build a Machine Gun-Machine Gun-Shotgun-Chainsaw stack and then see it realized on screen in Sam's hands. It's like you're wielding some lethal version of a Looney Tunes gadget from the Acme factory.

The multi-path levels unfold in three different time periods and they're all (the ones I saw, at any rate) littered with pickups of various types. You can grab standard health and armor boosts, weapons, Gun Stacker connectors, even collectible pies—the Mommy's Best logo—that unlock the game's challenge rooms.

There are some creative uses of the environments as well. At one point, Sam finds himself trapped at the bottom of a pit, which enemies are constantly spawning into. You start to notice as the bodies pile up that they don't disappear; indeed, the goal here is to literally fight your way out of the pit on a mound of enemy corpses. Similar tactics are required at another point to get Sam across an un-jumpable pit filled with spikes.

There's still some tuning to be done and some bugs to be squashed, but Serious Sam: Double D is immediately entertaining even in this alpha build. Unless something goes very, very wrong prior to release—which should be happening sometime this month—this is one that arcade shoot 'em up fans and Serious Sam fans alike will want to make room in their calendars for.

The PC version is expected on the Impulse and GetGames download service this month. No date yet for the Xbox 360 version.

Adam Rosenberg is a freelance journalist based in Brooklyn, NY and living at the whims of his lovable chow, Loki. You can find his work plastered all over the Internet, or just follow him on Twitter @geminibros.