Some googling gave me a couple things to try but no dice. OSX version 10.10.3 2014 MBP bought the game from the steam sale.
I got past the loading screen once but now I get the initial splash (no music) and it dies halfway through the AtomicTorch logo. Going to need a quick fix or it's refund time, please
https://drive.google.com/file/d/0B2cvFEqK_kZoMk5TcE1UbWY2TWs/view?usp=sharing
apparently didn't search hard enough. Disabled steam overlay and it launches fine
Hello!
Yes, disabling Steam overlay UI usually helps with this issue.
We're trying to fix it in the upcoming v1.4.1 update, it will be available in Steam early next week.
Regards!