Metal Gear Acid mixes the astounding aesthetics the series is famed for with a unique card-based battle system. Assuming the role of series hero, Solid Snake, Metal Gear Acid is set in the year 2016 and begins as a terrorist faction hijacks a jumbo jet carrying a man understood to be the next US President. The terrorists demand the handing over of a project known only as 'Pythagoras', which is understood to be in development on the isolated Lobito Island.

Viper card:
Enter VIPER as a password to get a card featuring Black Arts Viper from the Metal Gear Solid on the Game Boy Color.

Jehuty card:
Enter JEHUTY as a password to get a card featuring Jehuty from Zone Of The Enders. This card will destroy all equipment and equipment level-ups in the current room.

Karen card:
Enter KAREN as a password to get a card featuring Karen from Policenauts.

Mika card:
Enter MIKA as a password to get a card featuring Mika from Snatcher.

XM8 card:
Enter XMEIGHT as a password to get a weapon card with 50 attack, 60% hit, 5.56mm bullets, 6 shots, 70% reaction, move 6 spaces, knockback, and burn.

Bikini models:
Enter KOBE as a password to get a card featuring Japanese model Kosaka Yuka in the North American version of the game. Note: Enter SABRAGE as a password in the Japanese version, in which Snake will also get a nosebleed, but has no effect on Teliko. Enter LEPUS as a password in the European version of the game.

Enter UMEDA as a password to get a card featuring Japanese model Asaki Yoshida in the North American version of the game. Note: Enter NOMEL as a password in the Japanese version, in which Snake will also get a nosebleed, but has no effect on Teliko. Enter CYGNUS as a password in the European version of the game.

Enter YEBISU as a password to get a card featuring Japanese model Saitou Yuu in the North American version of the game. Note: Enter ELYTS as a password in the Japanese version, in which Snake will also get a nosebleed, but has no effect on Teliko. Enter SERPENS as a password in the European version of the game.

Enter ROPPONGI as a password to get a card featuring Japanese model Shibuya Eri in the North American version of the game. Note: Enter MAEB as a password in the Japanese version, in which Snake will also get a nosebleed, but has no effect on Teliko. Enter GRUS as a password in the European version of the game.

Play as Teliko:
Successfully complete the Residential Zone mission.

Solid Snake (MG) card:
Successfully complete the game.

Raiden card:
Successfully complete the game two times.

Link battle option:
Successfully complete Stage 06 to unlock the "Link Battle" selection at the "Options" menu under the "Intermission" screen.

Obtaining rare cards:
First, make sure your game is saved. If you have a lot of points to spend, go to the card shop. Buy all packs in the shop for the rare card you want (for example, Liquid Snake, Genola, Solid Snake, etc.). If you do not obtain any cards you want, go to options then return to the title screen. Reload your game and do the same thing until you get the desired card.

Special scenes:
When you start for the first time, you won't probably get the special scenes from Metal Gear Solid, Metal Gear Solid 2, and Metal Gear Solid 3. To do this, have all or most character cards. For example, start a new file after getting to the Leone battle. With the new file, you must get all the character cards. When you use it, you should have a video sequence from when Snake met or fought the character on the card. Note: Not all character cards will have special scenes.