A more traditional description for Borderland would be, "cooperative FPS with Diablo-esque mechanics." You start off by picking a character: Roland the gun-toting soldier, Lilith the stealth/magic femme, Mordecai the sniper, and Brick the boxer/tank. Then you guide that character through a grand journey with multiple quest hubs and dungeons; most of the quests are of the simple "go to a dungeon and kill/collect x amount of y." My first playthrough, where I mostly focused on going down the critical path with a little bit of (but not nearly all) of sidequesting, took about 27 hours. By the way, the overarching story of "finding the secret Vault while guided by a mysterious woman who talks to you in your mind" is just serviceable; it's there to give you a reason to kill things, but don't expect anything more in-depth.
But while games like Fallout 3 and Hellgate: London still use under-the-hood die rolls to determine first-person results, Borderlands, courtesy of Gearbox's experience in the FPS genre, uses actual skill in its combat. You don't aim center-of-mass and miss due to an incredibly unlucky dice roll -- you simply hit. While there isn't super-detailed location-based damage (you can't shoot a gun out of someone's hand or cripple their legs), at the very least, a bullet to the head counts as a critical hit. Also, the general aesthetics of gunplay are well-realized; shotguns impart oomph, sniper rifles sound off with a satisfying crack after each shot, and submachine guns blurt out bullets at a furious rate. Curiously, the only gun that seems off is the rocket launcher; there doesn't seem to be enough splash damage, and sometimes I can't even tell where the rocket itself will go. Rocket launchers are the one weapon type that I underutilize in thirty-five hours of play.
Layered onto the FPS gameplay are the two RPG mechanics that directly and reliably tickle my reptile brain: the skill tree and the randomly-generated loot. Like in Diablo 2 and World of Warcraft, each character has three distinct skill trees to apply skill points towards. So even if everyone plays as the somewhat-overpowered Roland, one player might spec him to be a damage dealer while another goes for the medic build. I personally like having Brick be a melee-monster, while others tend to bulk him up as a pure tank. Plus, at a cost, you can re-spec anytime (something that Hellgate should have done). Even though the moment-to-moment gameplay is, "shoot, shoot, shoot," these skill trees add just enough to help each character feel distinct.
The loot system also pulls from Diablo, in that a bunch of adjectives in the name determine weapon factors such as damage, firing rate, magazine size, and so forth; you can open a chest or loot a basic enemy and get a surprise in the form of a SMG with a scope, a large ammunition clip, and explosive rounds. Besides guns, randomly generated gear includes power shields, grenade modifiers (my personal favorite is Transfusion, which saps enemy health and transfers it to you), and support mods that affect skill tree allocation. Heck, the color that indicates rarity is straight out of WOW (white, green, blue, purple, and orange); this is the first FPS where I proudly boast of wearing "mostly purples." Besides the randomly generated guns, there are also "uniques" with specific properties; such as a revolver that fires wildly inaccurate rounds (due to its previous owner having only one eye), or the affectionately titled "Boomstick" shotgun that pelts six electric grenades simultaneously per trigger pull. Borderlands is tuned to the inner lootwhore of action-RPG aficionados.
Borderlands famously underwent a visual style overhaul for the better. The use of strong lines and bold color for a more "painterly" style makes it stand out among other Unreal Engine 3 titles, and alleviates the fact that, man alive, you're looking at a lot of post-apocalyptic wasteland with occasional industrial wasteland or interior (at least there's a snowy mountaintop near the end). The visuals also serve as the gateway for the over-the-top silliness that permeates the game and turns it into a charming and goofy experience. It's fitting that enemies become piñatas -- with damage-inflicted substituting as confetti and guns/money/shields/ammunition as candy. It's internally consistent that being a medic means that your bullets actually heal allies when shooting them. It allows for a game where a psychotic little person wearing a makeshift crown becomes a feared foe. It's where Mordecai's special attack has him throwing a bird at foes (which also causes money to fall from the sky); where a shotgun can sport a sniper scope while firing acid bullets.
So when you add multiple (up to four) players to all that, it simply works. There's something to be said about collectively experiencing panic when the screen gets filled with "badass level 35 angry shotgunner midgets" (actual game term). When you add players, the game adds tougher (and sometimes even more interesting) enemies to compensate. The characters complement each other; it's great to coordinate a situations such as having Lilith sneak by to unleash a fire attack, followed by Roland laying down a gun turret to help fight baddies, and end with Brick running around while punching stragglers. Though, like an MMO, you'll want to be relatively close in levels to each other -- otherwise you have a situation where either the lowbie can't keep up and dies a lot, or the high-level player get bored. I personally didn't mess much with the PvP features, but I can see players who, after using the New Game Plus mode to run through the story multiple times and reach the level 50 cap (my main, after 27 hours, is level 35), then moving onto PvP arena fighting
In fact, the great multiplayer smoothes over some of the biggest irritations with single-player; playing Borderlands alone is an invitation for occasional aggravation and boredom. The enemy A.I. is simply dumb for the most part. Most enemies follow the "run straight at the player" tactic, with only the Crimson Lance (end-game baddies) utilizing any actual tactics. Fine for when baddies swarm you and your buddies, but dreadfully uninteresting when playing alone. The additional enemy types added for multiplayer help with the variety problem; alone, you face hundreds upon hundreds of the same bandits and skags. With friends, at the very least, more interesting variants of those same foes show up.
The death mechanic gives you a chance to kill an enemy while bleeding to "get a second wind," and prevent actual dying and respawn. This, plus the ability for players to revive each other, is great for multiplayer. It's the right balance of tension, risk, and reward. It's not as interesting alone; it downright sucks such as in situations for when you get taken down but there's no one to fight, and you're forced to pay the respawn fee.
The boss fights also suffer in single-player due to a combination of poor/uninteresting A.I. and design, and the save mechanic. These encounters generally boil down to "either shoot all of your guns at the boss while circle-strafing, or shoot the guns at the boss' glowing weak spot." The last boss fight on my own felt extraordinarily anti-climactic; I was able to exploit it by hiding behind a column and popping out for the occasional easy-to-do critical hit (it doesn't help that the actual ending can either be described as "eh" or "terrible"). Like the enemies in general, the lame (and occasionally cheap) boss fights just feel better when gunning with a buddy or three.
Even as such, multiplayer still can't fix odd quirks that whittle away the experience. Such as the long walks/drives before you unlock fast travel. Or the times when Borderlands forgets that it's in first-person and tries to be a platformer. Or that the sole vehicle I've driven in nearly 30 hours of play is a two-seater (no four-seater seems odd for a 4-player co-op game). Looking at an item on the ground to loot it takes getting used to, and so does not having a minimap (odd, since Diablo 2 had one). The informal "drop stuff on the ground on the honor system" is the closest we have to a trade interface.
Call it a first-person Diablo, an evolution of Resistance 2's co-op mode, Monster Hunter for the west, or a party game for FPS gamers. Call it the best example of the transformative power of multiplayer. Whatever you designate it, Borderlands is a decent single-player FPS/RPG that simply becomes great -- when playing with others. Besides, sheer midget panic is something that has to be shared with friends.
Overall Score: 9/10