Thanks for the comments. I think from now on, if anyone asks I'll just say "why, yes, impending doom was exactly what I was going for".
Sound effects are generally the last thing I do, so the game is silent for about 90% of the development time and I never have an idea of what I want the game to sound like. In this instance, I just wanted to give the player some audible cues to let them know something was happening, like enemies spawning in. It's also quite difficult making sound effects in Costa Coffee when there are screaming kids about (true story).
Quote: "I am looking forward to doing something different than drawing pictures all the time."
That's the other one, when a project turns into a grind and you got to just grit your teeth and get on with it. Stay strong.