I haven't played CoD in ages but last I heard that people were using a CoD 4 version known as 'pro Mod' you could google it. Also, for what you are planning to do, I recommend using Evolve rather than tunngle.
I have heard that it is now unplayable in countries which do not support handful of third world countries not recognized by Sony like Pakistan. Steam is a true global platform.Then they cry that console gaming is dying.
You reap what you sow. This is what happens when you take away choice from consumers. Even with 88% split going to developers, they can't recoup costs. Meanwhile, Helldivers 2 is a massive hit for Sony thanks in big part to Steam.