Keep Shooting The Enemy Until He's Health Reaches Zero, You Can Do This By Using The Weapons That Spawn On Each Map.
Also To Make Sure The Enemy Is Dead, Keep Shooting Him Several Times, Until He Starts Spamming The Mic, Or RageQuits.

Now, You may Be Confused, Because I Didn't Explain How To Shoot With The Guns, It's Actually Pretty Hard So Follow My Steps.
1] First Of All, Attach A Mouse Into Your PC, A hamster Would Work Too.
2] Second, Transmit the Signal To the Brain To Lift Your Finger.
2+1] Finaly Press Mouse1.
DO NOT REUNITE THE SOVIENT UNION IN STEP 2+1.