Press J to add money.
As part of your country's elite strike unit you are trained to kill quickly and well. And that's why you are ordered to take out and kill the requested number of heavily armed targets in each stage. Collect money and grab all sorts of bonuses along the way as you try to get bigger and better weapons to have a chance to survive in the enemy territory for as long as it takes to finish your mission.
WAD = Move / Jump, Mouse = Aim / Shoot