The gun scene in the nuclear bunker

I think it was meant to force someone to do their job. Instead of sitting there having sympathy for the enemy, and betraying those he was supposed to protect.

The reality is that if one of the missile officers refused to turn their key, the other officer was supposed to shoot him for treason. And if that happened, the USAF General on board the Looking Glass aircraft or even the president still had the ability to launch the missiles from that facility. It was a much different time without the "touchy-feely love everyone and we must understand our poor enemy" society we have. The fate of the nation was at stake and it took a special breed of men to become launch control facility officers.


"We're paratrooper lieutenant. We're supposed to be surrounded"
Captain Dick Winters, Bastogne, 1944

In 'Command and Control,' by Eric Schlosser - Eric relates to the reader that the ground support crew who designed, built and maintained the command pod where the keys were located (For Titan, anyway), knew that the key setup was easily defeated by running a single-contact wire from switch to switch under the desk.
So, the missile could be launched by mortally wounding the co-worker, 'hot-wiring' the key system and continuing with the procedure. Certainly a suicide scenario.

Missile launch requires that both men turn their keys at the exact same time. If the deputy shoots the commander because he won't turn his key the missile will definitely not be fired. So shooting him or threatening to do so won't do any good. That is why the US Airforce has redundancy systems. Therefore, if this missile base did not fire, for whatever reason, another would as backup.

So you would just say, "Kill us all, I don't mind. Then go have happy lives"?

It's pretty easy to understand why he pulled the gun on him and it's only a movie lol

That scene was bogus and was for dramatic effect only. In reality, precautions are intended to PREVENT an invalid missile launch, NOT to ensure a launch, which can still be triggered by the President. There are also backup officers who can take over if something happens to someone at the control panel (heart attack, etc.). Here's the lowdown on the "two-person rule":
https://en.wikipedia.org/wiki/Two-man_rule#Nuclear_weapons

The universe is not only stranger than we imagine, it is stranger than we can imagine.–J.B. Haldane

The USAF missile launch capsule crews did (and presumably still do) carry sidearms. As commented, there is a bit of Air Force lore as to what they are actually for when the guys are sitting 100 feet underground behind a 5 ton blast door. Air Force statement is that the guns are for the security of the facility. The reality is either what Wargames showed - to threaten an officer refusing to obey a launch order - or more likely, frankly as a suicide option once the missiles were launched and the officers are sitting there waiting for the soviet missiles to hit.

The Air Force always assumed that a portion of the launch crews would not obey the launch order. Two processes were put in place to get round this. One was the launch 'vote' in which a larger missile squadron was put under the command of 5 crews. The missiles would be fired if 3 of the 5 entered the correct codes which allowed for 2 fails (either refusals or destruction of the facility). The other option is that in an emergency, the launch crews can be over-ridden by the Strategic Command airborne alert plane (formerly the 'Looking Glass' plane). The missiles can be launched centrally from the plane which omits the ground crews and in effect is the process put in place in the movie.