XCOM: Black Ops
There are no aliens. Roswell never happened. You are safe.
Aliens only exist in Hollywood, and on LZ-426. ;-)
A recruit for this black op unit likely has a Military background and/or Scientific (pretty much any direction), Engineering or Cryptographic background. There is another, secret ingredient, but your characters will learn about that later.
The nation you come from is not that important – other than to give you flavor. You can hardly be a Nigerian Navy SEAL. Or if you are a member Nigerian Navy Special Boat Service don’t expect exactly the same background. Or you might have earned your pay jumping out of perfectly good airplanes.
Your character could just as well be a warrior/bodyguard from a 3rd world country, a landowner/reserve officer from Argentina or a emissions technician from the UK who was just using his term to finance going to university, studying astrophysics to fulfill his life-long dream of joining the SETI project.
Hey, you can even play a homestaying dad who earns his money playing online poker and being part of the local shooting club (although that would be really stretching it ;-)).