Overkill 3 isn't going for any accolades for complicated storylines. It follows a very simple process: fire, cover, reload, repeat. In fact, the cover mechanic is the game's mainstay, except for the odd level here and there when you're handed a machine gun and enough ammo to mow down your enemies.

The only thing that really changes is your enemies and the weapons you have at your disposal. Grenades are limited but a handy way to clear your enemies. A rocket launcher can be pressed into service to eliminate a drone or aircraft.

At times, you’ll have to make a run for it, avoiding sniper fire. But you aren’t in control of the run; instead you have to swipe through targets as they appear on the screen so your character will roll and dodge the bullets. Fail to swipe and your character is cut down.

You can boost your firepower with upgrades. Add a flashlight or a tactical laser, a new grip or even just a fancy slogan; anything to help you take on the enemy. That will require game currency, which can be earned or bought – the in app purchase raises its head once more. Armour gives you better protection, obviously, and that can be upgraded as you progress through the game in a similar way.

Ultimately, the shoot and cover mechanic gets a bit old, but a couple of things save the game. First, there’s the fact that levels are reasonably short, so you can pick it up and put it down as you please. Secondly, there are goals to complete – some as simple as making it through the level, others will give you a $ amount to earn in a round. That gives you something to aim for, even if it seems insignificant at the time.

A good mobile shooter.