When it was first announced that the Metal Gear Solid series would be coming to the PSP, everyone was overjoyed. At first glance, it looked pretty great too, with the top-down perspective of the original Metal Gear Solid, stealth, greeny-blue military bases, and... are those battle cards I see popping up all over the screen? Ahh crap. Yes, Metal Gear Acid was the Solid Snake adventure that nobody expected or really wanted. One of the great sagas of the video game medium was transformed into a turn-based trading card game, and while it wasn't as good as the proper portable MGS games that would come later, it was actually pretty fun. Each encounter in the game is played out using a hand of cards that includes weapons, melee moves and characters from the series. It was a highly tactical affair, as you had to carefully weigh up each action and each grid-based step you take, sneaking past enemies or attacking them to reach the end-of-level objectives. As you combine cards and learn the ropes, you'll soon see that the depth of strategy here is much greater than your average Metal Gear game. Acid's unique gameplay hook earned it a cult following of card game fans, prompting an improved sequel to come out a few years later. An obscure spin-off success story, if ever there was one.