SNK's Metal Slug series is one of the most beloved 2D side-scrolling shooters of all time, right up there with Contra. And fans of the originals were no doubt pleased when the twitchy, skillful, and delightfully pixelated games made their way to Android. So for the series' first foray into a new mobile title, it's only natural that SNK Playmore would make... a tower defense game.

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Yeah, this ain't your daddy's Metal Slug. In Metal Slug Defense, you recruit soldiers and build structures in a real-time, one-lane defense layout, sending them headlong into the enemy base with no real direct control. You can strategically use your action points on offensive units, defensive units, or on upgrading your hero to get points faster, but there's none of the twitch-based, bullet-filled action that the series is known for. The titular Metal Slug tanks make an appearance as a super move, plowing over enemy units to explode into the opposing base. Whittle down your opponent's base before he does the same to yours and you win the stage. Rinse, repeat.

The mechanics will probably be a little dry for true fans of Metal Slug, but the cartoony art, music, and characters from the series are present in abundance. The game includes online battles with Google Play Games support for multiplayer. Unfortunately, it's also free-to-play with (all together now) a dual-currency in-app purchase system.

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Oh, the glory and honor of valorous combat! Here's 180 Medals of Honor for six bucks.

Most of the time victorious battles will net you cash which you can use to upgrade individual units, but to buy new units or power-ups you'll need "Medals," which rarely drop in-game but can be bought with real money. It's safe to say that online player-versus-player battles will be slanted towards anyone who's spent time grinding or spent money skipping ahead.

Metal Slug Defense is a free download for Android 2.3.3 or higher.