For hardcore Metal Slug fans who are also DS owners, Metal Slug XX on the PSP might look awfully familiar to you. That's because it's a slightly revamped port of Metal Slug 7 on DS from last year, and aside from adding the ad-hoc two-player mode, it doesn't differentiate itself very much from the original title. With that in mind, if you don't plan to play this game with another person in tow, then you should probably think about skipping this particular release altogether. For everyone else, though, Metal Slug XX is worth a look, especially at the $20 price point.

If Metal Slug XX is your introduction to the Metal Slug series, then let me give you a little background. It's a difficult, often punishing, shooter series that hails from the old-school arcade and Neo-Geo days. It features SNK characters (most notably the protagonist, Marco Rossi) battling it out against an evil army led by General Marden, who apparently has an endless number of enemy troops and weaponry. The Metal Slug series is known to be maddeningly difficult, and Metal Slug XX doesn't change that notion. You move along each stage, mostly going from left to right, shooting endless bullets at enemy soldiers who often die in gruesome, yet sometimes hilarious, manners.

Along the way, you'll free POWs, who are your primary means of getting weapon upgrades, and you'll occasionally step into a slug vehicle, which is a tank-like weapon. At the end of each stage, you'll encounter a huge boss that requires some quick timing, lots of grenades, and a little bit of luck to hit its multiple weak spots and kill it. It's pretty standard fare as far as 2-D action titles go, but it's well animated, the 2-D sprites are very well done, and the music is really solid. It's not going to win any game of the year awards, but if you're already into this kind of thing, it's worth checking out.  

If you thought that Contra on the NES was a difficult game, then you haven't seen anything yet. The punishing difficulty can wear a little thin, but this particular title features a very lenient continue system, even more so than the limited number of continues given in Metal Slug 7. If you die in Metal Slug XX, you simply restart where you left off, so you can switch between the playable characters every time you face the continue screen. You could make the argument that it sucks the challenge out of the game, but it's also feasible to place your own limitations on the continue system if you plan on challenging yourself. Otherwise, this unlimited continue setup makes if far more accessible to a more casual action fan who wants to see how the game plays out.

The cast in Metal Slug XX sticks to the fan favorites and doesn't offer up surprises, at least not on the UMD. Aside from the protagonist, Marco, there lineup includes Clark, Eri, Fiolina, Eri, Ralf and Tarma. For the PSP, Leona from King of the Fighters is a downloadable character, which is a feature that the DS didn't have. It remains to be seen whether there will be more DLC content of this nature, but I wouldn't be surprised to see a few more. The DLC only costs $1, so it's not a big deal to pick up, either.

As far as weapon selection goes, most of the fan favorites are present once again, with a few additions.  You'll start off with a basic pistol that has unlimited ammo, but you'll quickly gain access to an automatic machine gun, shotgun, homing missiles and a large laser gun. There is a new weapon in the form of the Thunder Shot, which has homing capabilities mixed with a big bolt of electricity; it's ridiculously effective but has a pretty limited use. You can also store two weapons at once and switch between the two with the left and right shoulder buttons on the PSP. All of the extra weapons have limited ammo, though, and you'll usually want to keep one in reserve for the boss fight. You also come equipped with a certain number of grenades, which are definitely handy for taking out most of the ground troops, structures and various tank weaponry.

As I mentioned earlier, you can control various slug types as vehicles. These come equipped with health bars, and once they hit the maximum damage threshold, you're given a limited amount of time to eject from the vehicle before it explodes. The slugs are fun to pilot, but the controls are also a little frustrating; your movement and aim are tied to the same button on the directional pad, so if you're moving forward but need to shoot behind you, you have to start backing up to get the gun pointed in that direction. It's not an ideal setup, but at the same time, most of the previous games have used a similar control scheme. Maybe I'm a little spoiled by the creation of dual stick shooters like Geometry Wars, but I think Metal Slug would probably benefit from a similar setup when it comes to vehicles. The Slug Gigat is a really cool addition that's only used for one level. The Gigat is a giant robot, and you absolutely rip up the level, and while it removes a lot of the challenge, it's introduced far enough into the title that you'll welcome a brief respite from the difficulty.

Metal Slug XX is separated into seven stages, with three difficulty levels. Playing through the game on normal difficulty, I finished it in 47 minutes, which is obviously pretty short for most modern games. However, the Metal Slug games have generally benefited from short play times so that players could improve with each playthrough in score and overall time. It's definitely something you can play multiple times in order to best your score and time, and the short completion time actually makes it far more likely that gamers will replay it. There are some hidden areas tucked away in different stages that feature completely different enemy types, giving you another reason to play through the game two or three times.

The addition of two-player co-op to the PSP version of the game is going to be the biggest draw for most. Every Metal Slug title up to this point, minus Metal Slug 7 on the DS, has featured a co-op mode, so it's nice to see it return. The game is a lot of fun with two players on board, and the challenges are more feasible to complete. It would have been really cool to also have this featured as an infrastructure online mode, but I'll settle for local co-op through ad-hoc.

If you're coming into Metal Slug XX with the knowledge that you enjoy Metal Slug games, then you should absolutely pick up this title, unless you've already had your fill with Metal Slug 7 on the DS. If this is your first foray into the series, though, then I still think it's worth checking out because it's cheap and you can scale back the difficulty to Easy to utilize the unlimited continues. Otherwise, you'll pull out your hair in frustration at the difficulty level of these particular games. As far as the franchise goes, Metal Slug XX is pretty accessible, and most action-oriented gamers will enjoy it.

Score: 8.0/10