Thank you for the logs!
Based on my research so far, there are 2 possible solutions:
1. I need to upgrade my version of Unity as this may be a bug fixed in Unity 2018. This is assuming you are using Windows 7, I think.
2. This may be an issue with Steam itself. Try following the instructions here:
https://steamcommunity.com/discussions/forum/1/864973032790233112/If #2 doesn't help you...
it may be a while before I can upgrade Unity to the latest version. There are always a lot of things that break when I do that and I'll need to fix them all before uploading a new build. In the meantime, feel free to refund the game until there is a fix. I hate the idea of someone spending money on a game that doesn't work for them.
...
Read more