Metal Slug is viewed from the side. The objective is to move through six stages, defeat enemies, rescue prisoners of war, collect weapons, and destroy a large boss at the end of each stage.

Players walk, jump, fire in eight directions, throw grenades, and use mounted vehicles when available. Weapon pickups provide limited ammunition, while the standard pistol has unlimited shots. The Metal Slug tank adds a separate armor and ammunition system, but it can be destroyed.

The arcade campaign is single-player or cooperative for two players. Progress is based on clearing stages rather than experience levels; score increases through enemy defeats, rescued prisoners, collectibles, and efficient play.

Keep moving, but avoid jumping blindly into enemy fire. Learn the timing of enemy waves and use grenades against clustered soldiers or exposed bosses.

• Rescue prisoners whenever it is safe; they can provide weapon upgrades and increase score.
• Conserve heavy weapons for armored targets and bosses, since their ammunition is limited.
• Use the Metal Slug’s cannon and machine gun separately, and abandon the vehicle before it is destroyed if necessary.
• Memorize boss attack patterns rather than relying only on rapid fire.