Reload after a battle. It's always better to have a full clip in anticipation of the next fight rather than finding yourself ambushed and having to reload when faced with an enemy.

Explore each level thoroughly to find cash pickups vital for upgrade purchases. They're often in hidden alcoves and tucked in the shadows, so look carefully.

Saving money for useful upgrades is often preferable to spending the money you have on an upgrade immediately. For example, extending the duration of your paralyse ability is three times the cost of increasing your pistol clip, but it's a more powerful upgrade.

Select ammo caches and some terminals require completing a hacking mini-game. An iteration on the first game's mirror puzzles, here you have to tap switches to bounce a circle into a goal. For some puzzles, you may have to tap switches multiple times as the ball travels through the stage.

If you played the original N.O.V.A. expect a treat when you log online for multiplayer: bonus experience and a special suit of armour.