It's been years since the aliens invaded and I still haven't figured out how to even pick up a pistol. My favorite things to do are hide out in the open and run directly at the aliens when they fire at me. If possible i stand right next to them so my chance of getting hit by friendly fire are as high as possible.
I wouldn't call it a retcon really. You can view the latter half of the first game as the aliens capturing you and putting you in a simulation.