Originally released for the PC as Serious Sam Double D in 2011, this iteration of the Serious Sam franchise is an independent take on Croteam's irreverent FPS series. Developed by Mommy's Best Games, Serious Sam Double D moved Sam from his 3-D world into a 2-D, side-scrolling shoot-'em-up. It was somewhat like the Contra games, only crazier. Since the XBLA release hit (digital) storefronts more than a year after the PC version, Mommy's Best Games didn't want to do a straight port. Instead, Serious Sam Double D XXL adds weapons, enemies, upgrades, levels and a second player to the mix, ensuring there is enough new stuff, even if you've already played on the PC.

The concept behind Serious Sam Double D XXL is simple: shoot everything. And in this game, there is almost always something to shoot. Enemies of all sorts come at you, teleporting in at a moment's notice. Sometimes they're in front, sometimes above, sometimes behind. In short, you're always moving and always shooting.

Given that shooting is a core feature, it's that aspect that the developers decided to focus on. In the PC release, Serious Sam Double D introduced the concept of "gun stacking." The idea is that Sam can use special connectors to stack up to six guns at once. All the guns in a given stack fire at the same time, giving you customization as well as massive offensive power.

For Serious Sam Double D XXL, the customization is taken one step further. This time around, you have the ability to purchase gun upgrades at the local merchant. Some are basic, such as increased ammo capacity, while others change the function of your gun. For example, one gives you an air buffer (slowing down the rate of fall) as long as you are firing. Another upgrade makes one weapon shoot butter, while a third turns grenade ammo into beetles. Weapon upgrades are gun specific, but each gun can be collected multiple times, and there are four options per gun. You can spend a lot of time tweaking your weapons.

As silly as it sounds, the gun stacking concept is actually quite engaging. It taps into the "perfect build" aspect of gaming that is pervasive in many action-RPGs. Tweaking with the upgrades, mixing and matching gun stacks, figuring out what combinations work best in which situations — it's a whole lot more enjoyable than it sounds. That isn't to say the shooting isn't fun — it is. The frantic nature of the enemy onslaught is the best part of Serious Sam Double D XXL.

Co-op is also an enjoyable addition, though it is limited to offline play only. There is no option for co-op over Xbox Live. While playing co-op, both players share weapons and gun stacks. Achievements are also limited to the primary profile, so if you want to unlock them for both players, you'll have to play through the game twice.

There is no split-screen option for co-op, instead, play is on a single screen, with the two characters are essentially tethered together by an invisible cord. If separated, the off-screen player reappears in a bubble of shame. One nifty thing is how the game deals with deaths in co-op. When your partner bites the big one, a series of special health icons appear around the corpse. The amount of health your partner starts with when he is revived depends on how many you collect.

By and large, the new additions to the game are all worthwhile, though there are two major exceptions: the new vehicle-based levels and the deathmatch arenas. The vehicle-based levels are completely forgettable and noticeably easier than the rest of the game. While we can appreciate the desire to try something new with the vehicles, the result is nothing more than filler. The same is true of the head-to-head deathmatch arenas, which feel like they were tacked on at the last minute to tick a box on the marketing form. You'll probably check them out once and then never load them up again.

The only other annoyance was the random slowdown that seemed to plague certain checkpoints. Sometimes, crossing a checkpoint would be fine. Other times, the game briefly lags while the game saved. Slowdown also popped up a handful of times when the game was overloaded with on-screen enemies.

In the end, it's best to think of Serious Sam Double D XXL as a "director's cut" of the original game. It's not perfect, but it is a noticeable upgrade from what we saw on the PC in 2011. While the crude art style and low-brow violence won't appeal to everyone, if fast action, twitch shooting is your thing, this is a game that's sure to please. Serious Sam Double D XXL is gameplay over graphics all the way.

Score: 8.0/10