After extensive research, we have found the updated unlock code for Alien Shooter 2: Conscription. The new code is:
Sigma Team originally distributed many of their games as "shareware" or free trials. Players could enjoy the first few levels before the game locked down, requiring a registration code to unlock the full version.
You now have the full, updated manual to dominate every level and unlock every secret the game has to offer. Happy hunting, soldier.