Trying to launch Rust through Steam on a Mac and I keep getting "Failed to start game (missing executable)"

Just like the title says. I got my Steam Key, entered it in properly, rust is showing up in my library. But when I Try to launch it on a Mac and I keep getting “Failed to start game (missing executable)”

I did the official steam suggestions on how to get rid of the error but it didn’t help at all.

What should I do?

Edit: Here’s a pic

Seriously? http://forum.facepunch.com/showthread.php?t=1320223

Geeze sorry. haven’t played rust or check the forums since like july and