Game is running very well. My 'Microsoft Xbox 360 Wireless Adapter' isn't detected by the game. Neither with the xpad kernel module, nor with xboxdrv.

Current kernel and video driver

$ uname -a
Linux segfault 4.18.1-gentoo-r1 #2 SMP PREEMPT Sun Aug 26 02:59:28 CEST 2018 x86_64 Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz GenuineIntel GNU/Linux
$ equery l nvidia-drivers
 * Searching for nvidia-drivers ...
[IP-] [  ] x11-drivers/nvidia-drivers-396.54:0/396

More specs
My steam environment variables:

PROTON_NO_ESYNC=1
PROTON_USE_WINED3D11=1
STEAM_RUNTIME=0
STEAM_RUNTIME_PREFER_HOST_LIBRARIES=1