Metal Slug Attack is a tower defense game that draws on the aesthetics and gameplay of the Metal Slug series of arcade action games. In it, you must defend your base against waves of enemies built and commanded by your opponent. Players can choose from ten different head-to-head, co-op or single-player game modes.
Metal Slug Attack isn't the first Metal Slug tower defense game; it's a sequel to the earlier Metal Slug Defense. If you've played Metal Slug Defense, you'll be familiar with the basics of the gameplay, although the sequel streamlines some of the mechanics of the earlier game. You gather cards to create units which can attack enemy units or build defenses. One of the most powerful units is, of course, the Metal Slug, the high-tech cartoon tank from the arcade series. As you progress, you'll unlock new power-ups and game modes.
Like most mobile tower defense games, Metal Slug Attack is a tapfest in which you need to be constantly spawning and upgrading units. It's fast-paced fun, and like all Metal Slug games, it looks great, but the complex currency system can be confusing.