I like the building SFX.
I think the "Yes Master" SFX is too hard on the ears, and would become taxing to listen if it came up a lot in the game, but if it was only once or twice. Maybe it would be a little less grating with a subtle low-pass filter
Your music has a good vibe and feeling to it. Good instrument selection. Maybe it sounds a little lonely for a game with a horde?