I don't know if any games such as those on steam accept payments in BTC but I know that you can play games on sites for BTC. For example you can bet on sports with BTC, etc.
If it's not a thing perhaps you can suggest it!!
I too haven't come across any such website other than steam accept bitcoin in terms of bitcoin. I think in future when bitcoin get used as the only source to use in gambling sure we can see more websites similar to steam accepting bitcoin in terms of bitcoin directly or through an intermediary service provider.