Nam-1975 is an action packed cross-hair shooter. You are looking over your shoulder 3rd-person style (in the foreground) and firing at the enemy by using your cross-hair to aim and several different weapons to attack.
There are three buttons to go along with the joystick: Gunfire, Grenade and Run/Cartwheel. Both the gun and grenade functions can be upgraded and there is a count near the grenade icon on the upper left of the screen to tell you how many grenades you have left.
You have to constantly scramble left and right across the bottom of the screen to avoid incoming fire. This makes your aiming a little difficult as it always is in games like this since your joystick simultaneously controls both your aiming cross-hair and your movement. So it's hard to shoot accurately when you are running for your life, and if you stop to aim, look out!
To help with this, the 3rd button is the run/cartwheel button. If you push/hold down the button, you run in the direction you are pushing the js (left or right). If you push the button and pull the js down and left (SouthWest on a compass) or down and right (SE), then you cartwheel to the left or right, quickly evading any incoming fire that's about to smoke you.
There are power-ups and bonus scores that are sometimes tossed at you by dying enemies. They sit on the bottom of the screen until you go pick them up (time limit?). Also, any upgrades are lost when you die.