I tested the game and with default video settings it did hang sometimes, but dialing video settings down, the Rocket League works fine with Debian testing Xfce. Oipaf ppa and custom adg5f drm-next-4.11-wip kernel. Rx 460 is my gpu and I have tweaked the kernel to be fast and stable, see: https://bugzilla.kernel.org/show_bug.cgi?id=193651