Game development is different from software development in a sense that you need to be inspired in order to start working with great productivity. Programming is a creative process, especially when you're programming without a blueprint (you experiment or you're trying to reach a conclusion through iterations).
People around you tend to influence the way you code. If the environment is too noisy and filled with off-topic discussions, your productivity goes down the drain quickly.
I draw my inspiration from:
* soundtrack music
* people around me
* early mornings
* late nights
* office lightning environment
* chill Twitch sessions in background
In this post I'll focus my attention to background music.
I get in "the zone" with great movie or games soundtracks or compilations of different ambient sounds. Sometimes having in background a chill streamer like Squirrel helps. What matters most is to isolate yourself from the outside distractions.
I've started using noise cancelling headphones from Platronics but I had to give up those because my ears hurt when I do long programming sessions (even with 10 minutes breaks).
I've reverted back to in-ear Samsung stock headphones - the ones that come with your smartphone. These are less cumbersome, easy to migrate from laptop to phone and most importantly my ears don't hurt.
There is an obvious sound quality loss from 200 euro headphones to these stock ones, but it doesn't matter that much!
Here are some killer game development/programming playlists. Check them out and let me know in the comments if they improved your focus or productivity:
Repetitive chill music
Blade Runner style
Update: 19 March 2019
I might have found the greatest programming music of all time http://www.behaviormusic.com/projects/splinter-cell-double-agent-soundtrack/. You can also download it or listen it in-browser. I like the way the sound is mixed and the atmospheric soundtrack overall.