Developed by GNI & Sesi Soft, Metal Assault (often referred to as MA) is a free-to-play 2D shooter game with movement based on WASD keys and weapon aim is mouse-directed. You gain experience through completing missions, quests, and through PvP and PvZ (player vs zombie) battles. However, there is a difference between level EXP and license EXP, which increases your proficiency with different types of weapons.