Sound effects can add a lot to a game. Even just ones that you do with your voice. People screaming, animals roaring, machinery rumbling - act them all out. It helps build and maintain the atmosphere.

And then when the players are deeply immersed in the game situation, sometimes a tiny sound can make a huge dramatic impact.

Just stop speaking for a while. Sit there and say nothing. Do nothing. It may take a little while, but the players will eventually realise you're not responding to anything that's happening or telling them what's happening. Silence will descend for a few seconds.

Then hit them with the pin-drop.

Transcript

R2-D2: Ah, the power!
[SFX]: wwhhooHHRRHHH!!! {ship's engines fire}
R2-D2: The sense of immense control!
R2-D2: Commanding a massive engine of war!
[SFX]: wwhhooHHRRHHH!!! {ship re-enters Coruscant's atmosphere}
R2-D2: The unshakable feeling of being destined for greatness!
[SFX]: snap! {back of ship falls off}