SEGA Genesis Classics

Load up Alien Soldier and once you're on the main menu, press on 'Game Start'. Once the next screen has loaded, you'll now have a choice of 6 different weapon modes. Go ahead and select 4 different types by pressing , and then keep pressing it to skip through the other options and pages so that you finally enter the game.

Once you're in the game, you'll now need to shoot all 4 of your weapon mode - take note that you do not need to get a kill with them. To shoot, press (B) and to swap press (A) and then /// to swap between them. Press any button to select a new weapon mode, press (B) again and repeat the process to unlock the achievement.