On its face Mercenary Kings is a Metal Slug clone, a 2D game of neon bullets and cartoon decapitation. Under the hood it's a slew of anything that would fit: Monster Hunter's big prey, rare items, cooking buffs, and time limits, Dead Space 3's gun crafting, and an active reload snatched from Gears of War. Mercenary Kings is a 2D game that looks and shoots like an arcade side-scroller, but, mechanically, is a tangled mess of hit points, damage values, level-ups, and loot drops.

It definitely shares the intricate animation of Metal Slug, a series known for heads popping like water balloons, frame-by-frame blood spray, and gigantic, fire-orange explosions; exceptionally violent, but over so quickly, and rendered in such a goofy style, that it makes even murder seem like a wholesome fun. Mercenary Kings overflows with that same ludicrous violence, as well as Metal Slug's penchant for the absurd. Slap together enough drumsticks in Mercenary Kings and you'll build a mewling cat gun. Do battle with multiple variations of the "puppy tank," whose devastating adorability pales in comparison to their flesh-and-blood, eyepatch-clad doggy pilots, whose dazzling cuteness, in turn, can't even hope to match that of Anvil, a beret-toting Shiba Inu who (for a second or two) leads a la Résistance-style guerrilla war against the occupying forces of CLAW.

There's enough story, related through bite-sized Metal Gear codec calls, to fill the cracks between missions (the ones not already occupied by surprisingly long load times for a 2D game, anyway), but not so much that it's overbearing. Like the 80s and 90s side-scrollers that inspire it, Mercenary Kings is brief, sometimes to the point of error. The lack of hand-holding provides a sense of discovery that many contemporary, tutorial-centric games lack -- what it was like to play Mega Man before you'd memorized the proper level order -- but, on the flip side, it'd be nice if the game bothered to tell you which assault rifles are burst fire and which are automatic. It might also be nice for it to partition off text like "this mission will unlock homing missiles," because then you might immediately prioritize it instead of writing it off as just another "collect eight junk" affair.

There's a lot of "collect eight junk" and a lot of "kill twenty guys." It's busy work, but it's busy work where you get to shoot a lot of guns. But this not Metal Slug, in which you obliterate fifteen soldiers and two buildings with every shotgun blast. There are rarely more than two or three enemies on the screen at once, and most are pretty good at taking a bullet (but less good at taking twenty of them). This is the Monster Hunter influence: multiple missions with different goals that take place in the same few, but large, levels. Like Monster Hunter, Mercenary Kings often sends you to kill or capture a oversized enemy, but its bosses are less meticulous battles against unthinkably large dinosaurs and more Mega Man encounters: tense fights in tight arenas against bosses with perfectly telegraphed attacks. Puppy tanks blitz you with anime lasers and giant missiles. Mech suits are slower, and only vulnerable in their open cockpit or from the rear. Most bosses have a great rhythm of evade and counterattack, but most of them also have gigantic life bars and a tendency to trundle away without ceremony in the middle of the fight.

Escaping bosses is more Monster Hunter flavor, but it's a little less functional here, in 2D. Every Mercenary Kings level is made of two or three big sections, sprawling wide left-to-rights and right-to-lefts that take a minute or two to traverse. Level designs start out straightforward, but eventually start including collapsing platforms, one-way routes, and long ladders blocked by intermittent electrical sparks. Rushing through dangerous areas can be difficult because player health is so low, but if you play too cautiously your target might be ready to wander off again by the time you catch up. It's an interesting system when you're playing at the top of your game, making good time across a level, and hitting all the jumps, but it's maddening when an elusive boss fires one lazy attack at you before he moseys off for the third time. Expect frequent re-dos by mid-game, either due to running out of time or lives. In a way, losing a mission is a source of enforced grinding, since you need raw materials to upgrade your life bar, make cybernetic mods that increase speed and regenerate health, and, most importantly, to build guns.

Gun crafting is Dead Space 3's Build-A-Bear with Borderlands pieces. A weapon's function is mostly determined by its receiver: shotgun, sniper, handgun, etc. Although you choose the magazine, the barrel, the sight, and the stock of your weapon, for the most part these bits are just there for stat increases -- more ammo for less damage, more accuracy for more weight -- but parts also have affinities for different types of ammo: homing missiles, shotgun spreads, armor piercing. Ammo types are one of the only ways you have control over a gun's efficacy other than gradually upgrading its damage value, so it's a bit of a bummer that the game doesn't take a second to mention that caustic ammo melts shields, for example.

You'll learn most of this through trial and error, which means wasted parts, and wasted time, on gun types you didn't really want, but you didn't know you didn't want until you tried them. Mercenary Kings is a game built for grinding, one whose content is wider than it is deep. There are dozens of missions, but only maybe a dozen maps. There are over a hundred enemies, but many of them are palette swaps whose only differences are elemental attacks and more hit points. Palette-swapped bosses get a new attack, usually, but electricity-shooting battle tanks act pretty much the same as fire-shooting battle tanks. You don't usually have to replay levels to progress, but you will if you're hounding for something specific. Coming out of a mission you'll probably have picked up the parts to build something, but it will probably not be the something you want. Sometimes that's a real pain, but only having parts for a new handgun when you prefer assault rifles creates diversity by necessity.

You'll usually get enough rusty bolts and nitroglycerin to build one or two nice guns in a single run of a given mission tier, but if you want to build something really specific you're probably going to have hammer at the same levels a few times. It can get a bit repetitive so, like with Diablo, Borderlands, and Monster Hunter, multiplayer is crucial both for the sense of camaraderie in overcoming a high hit-point target, but also to keep you from getting bored. Playing with friends smooths out some of the frustration with repeated level layouts, but you'll probably have to do it online. Couch co-op exists only in split-screen, and, even on a large TV, the per-player real estate is small enough to leave everyone squinting. It's too bad. The look of Mercenary Kings immediately triggers fond memories of arcade shooters and two-player Nintendo games, but the game itself is too sprawling to lock players on the same screen at all times. This is a something you should absolutely play with your friends, but, unfortunately, not really one you can play in the same room as them, unless you can stand the eye strain.

Mercenary Kings is really good at taking mechanics from all sorts of games -- side-scrollers, 3D action, first person shooters -- and making them work, all at once, in a completely different context. It is like those things, but it is not those things. Don't come into this expecting fast-paced gunslinging, because the precise movement and gravity-laden jumps will let you down. Don't come into it expecting a bunch of tightly scripted levels, because everything's a little one size fits all. But, for whatever flaws the game has, it's neat to see a bunch of disparate concepts gathered together in one space, even if what works here tends to work by brute force more often than it does by elegance. Mercenary Kings is a tangled mess of a game most of the time, but a fun one almost as often.