Like most first-person games of this nature, use your mouse to aim, and your left mouse button to fire. Reload with R, change your fire mode with F, and use V to peek over your sights (great if you’re using a bigger weapon). Between each wave, you’re able to spend the money you’ve earned on items, or you can repair your base.
Your base is being attacked and it’s up to you, and you alone, to protect it in this first-person action game. All you have to do to win Storm Ops is survive 25 waves of enemies. Or at least, that’s when you get a medal proving just how awesome you are. If you want to go on to prove just how much more awesome you are, you can keep going to see how far you can make it. As you defeat enemies, you’ll earn money, and you can use that money to repair your base, or equip new and better items to help you defeat those enemies more efficiently. It’s a cycle that would be broken if only the enemies looked right into the woods where you’re hiding.