Looks like these are related:
https://github.com/ValveSoftware/steam-for-linux/issues/4319
https://github.com/ValveSoftware/steam-for-linux/issues/4322
https://github.com/ValveSoftware/steam-for-linux/issues/4304
So this issue is affecting more and more games.
Fixed in latest beta client.
It seems on newer distributions (Ubuntu 16.04 64bit for me), Dying light, cities skylines and NeonXSZ are all broken unless you run Steam like so:
LD_PRELOAD='/usr/$LIB/libasound.so.2 '${LD_PRELOAD} steamIs this a Steam issue, or a bug I need to report somewhere else?
Thanks to this reddit comment: https://www.reddit.com/r/linux_gaming/comments/46sske/cities_skylines_crashing_on_launch/d07ljf9