- : Use the direction pad to guide the player through each stage. Press left or right to run in either direction. Press down to squat, and press up to enter through open doorways. You can also use the direction pad to aim the grappling hook forward or upward. When hanging from a platform, press up to climb up to the top.
- : Press the A button to fire your grappling hook. When pressed alone, the grappling hook automatically fires at a 45 degree angle. To fire the hook straight up, hold while pressing A. To fire the hook parallel to the ground, hold or while pressing A. Once connected to something, press the A button again to reel that grappling cable in and pull the player up.
- : Press the B button to fire your primary weapon. This is the weapon that you chose from the weapon selection screen prior to entering a particular stage.
- : Press the Start button to utilize an item that you chose to bring along with you into a stage.
- : Press the Select button to bring up a sub-screen which displays the map along with some information about your player, including how many bullets you have collected, and how many total are required to reach the next level.
- ++: Use this special combination of buttons to quickly exit from an area that you are in, and return to the map screen. This is especially useful if you brought the wrong communication device along, or are missing another required items.
You control the player, Ladd Spencer, throughout your adventure to take down the enemy army. Ladd only has two items at his disposal: his weapon and his grappling hook. While his weapon can help clear a path through the hordes of enemies that assault him and try to stop him in his tracks, it is the grappling hook that will help him navigate the treacherous hallways and corridors of the enemy's base.
Ladd can use the grappling hook in a few different ways. He can use it to knock enemies away before they get close enough to kill him. He can use it to grab items that are too far away to collect. Most importantly, he can use the grappling hook to grab onto ledges or platforms high above him. Once hooked on, he can either use the hook to swing across gaps to opposite ledges, or he can use the hook to pull himself up to the higher surface and continue.
Ladd begins the game fairly weak. It is possible to knock him out with a single touch of an enemy or their bullets. As Ladd collects bullets dropped by the enemy, his level of fighting experience will increase. For each level that Joe gains, he will gain one bar of health. Every time Ladd rises to a new level of experience, his life meter is replenished. Once Ladd has a health meter, he will not lose a life until the entire meter is empty.
If Ladd dies, but you have another life, Ladd will resume the game right where he died. If the game ends, you may only continue if you have collected continues during the game. These appear in the form of little eagles which resemble the enemy logo. When you continue, you will return to the map screen, and be potentially forced to retry the stage you died in from the beginning. The number of bullets you collected will also drop down to the lowest amount necessary for your current level.
Throughout the game, defeated enemies drop bullets. Bullets are akin to experience points in RPGs; when you collect enough bullets, you will rise to a new level of experience. Each new level of experience grants Ladd an extra meter of health. The most amount of health that you can accumulate is 8 bars. However, in order to accumulate these levels, you must collect the bullets. Bullets disappear if they are not collected quickly enough. Keep in mind that you can also use your grappling hook to collect the bullets while they are still bouncing on the ground. The number of bullets required to reach the next level rises incrementally. Refer to the chart below to determine how many bullets are required to reach each new level.