In Cruise missile interception game waits set amount of time for cruise missiles to hit the base and I have 1/3rd of in game time in my runs just waiting for this timer to end the mission.

Maybe we can count time until last plane/missile is down and there is no threats to base?

I second this

Yeah, that seems reasonable to me personally

Then how do we show time? Pause and show timer here, mission time on HUD at the same frame as the last thing goes down or separate timer?

I like the way you did the pausing and showing timer, but prolly for tight runs calling it at the death of the last cruise missile (as shown in the killfeed) seems most accurate to me?