If there's one thing that can be said with any degree of certainty, it's that SNK's Metal Slug series always remained fairly consistent over the course of their releases. The gameplay remained pretty much the same, with little more than a few tweaks here and there for good measure. Metal Slug 4 was developed by Korean firm Mega Enterprises and came onto the arcade scene in 2002 (during SNK's bankruptcy and prior to the company's rebirth as SNK Playmore), which might lead you to assume it's the black sheep of the family. The game has arrived on the Wii Virtual Console, and despite the troubled nature of its development, it offers fans of the the previous three releases plenty of explosive action to enjoy.
When it comes to gameplay, not much has changed over the years in the Metal Slug titles. You'll still spend the majority of your time running and gunning, while occasionally tossing an explosive and tackling a boss fight. You'll still have the ability to upgrade your weapon's fire-power by picking up power-ups, and as usual the titular "slug" vehicles play a big role in the experience. You will have to keep an eye on your vehicle's power gauge as if you take on too much damage it will begin to destruct, forcing you to bail out mid-battle — which, it has to be said, only adds to the fun.
Level design remains strong in Metal Slug 4 and there's plenty variation in each of the stages. You're going to be on foot a lot of the time, but there are a host of vehicle-themed spots in levels that will mix things up, not to mention the craft you can commandeer which come equipped with a wealth of fire-power. You can even charge the vehicles into a barrage of enemies with a quick press of the button for maximum carnage.
Play controls have always been very responsive in the series, so its no surprise that the developers pretty much left things as they were for this fourth release. Moving around is quick and easy, as are the shooting and explosive mechanics. Vehicles add a more intense element to the game and require you to keep an eye out for enemy attacks. No matter how long its been since you last played a Metal Slug game, it's always a bit like riding a bike in how quickly and easily you'll feel right at home with the game again.
Visually, Metal Slug 4 does a fantastic job of pushing the esteemed Neo Geo hardware — there is some really great colour variance and detail in the various backdrops you'll see throughout the adventure. While there's not a lot of depth to the scrolling, it's still sharp and detailed enough for you to overlook this shortcoming. The character and enemy animations are good enough — albeit a bit overblown and silly at times — but given the solid degree of variety in the different areas, it's easy enough to forgive.
There's a lot of great music to be found in the game and it never diverts too far from the synthesized chip tunes Metal Slug fans have grown to love over the years. The groaning noises from killed enemies do get monotonous, but they're nothing fans of the series won't already be familiar with.
If you can get past the fact that the Metal Slug releases have changed very little over the years and just enjoy Metal Slug 4 for what it is, you're likely to find a lot of run-and-gun action and variety to take in. The visuals are sharp and the soundtrack is exactly what you'd expect, so long-time fans should be perfectly satisfied with the game from this perspective. The new additions are minimal, but there's still something to be said for the simple, yet highly explosive action the experience offers up. Sometimes you just want to blow stuff up and you'll have plenty of opportunity to do so in this intense 2D shoot-fest.