The Long Dark on Gentoo

Ever since I first saw a letsplay video of The Long Dark back in early 2015, I wanted to play this game myself. Unfortunately at that time the game was only available as early access through Steam. Yet Steam is something that I really don't want to have on any of my computers. I prefer to have fully control over the games I have purchased and Steam simply is a system that prevents users from having full control over their games they purchased through Steam.
Luckily Hinterland Studios offers the game through Good old Games for a while now without steam as requirement and so I just bought the game three days ago.
For Linux systems GoG provides a self extracting (makeself) shell file containing the game. Once being executed, the script fires up a GTK+-2 installation GUI which makes the installation of the game really easy.
Running the game was quite easy, too. The game comes with a start.sh script that takes care of all necessary settings to start the game either on x86 or amd64 systems.
The game can be played with a game controller or with the standard keyboard. I decided for the keyboard as I am used to play 3D games that way.
Performance is quite well on my AMD Radeon R9 285 graphics device although with the graphics details being set to Ultra the game is a bit laggy. This might be a problem of the open source amdgpu driver not using the card's full potential or perhaps the firmware files still need some improvements, I don't know. Time will tell. For now I'm fine with the game being set to "only" High graphics details and I'm now trying to manage not becoming too addicted by this really fine game from Hinterland Studios.
I've tried to get a list of packages the game is using on my system. Here's what I came up so far:
CODE:
:~> for lib in $(ldd ~/GOG\ Games/The\ Long\ Dark/game/tld.x86_64 | awk '{print $1}') ; do qfile -CSq "$(locate "${lib}" | grep 64 | head -n 1)" ; done | sort -u
dev-libs/expat:0
dev-libs/libbsd:0
media-libs/mesa:0
sys-libs/glibc:2.2
x11-libs/libdrm:0
x11-libs/libX11:0
x11-libs/libXau:0
x11-libs/libxcb:0/1.12
x11-libs/libXcursor:0
x11-libs/libXdamage:0
x11-libs/libXdmcp:0
x11-libs/libXext:0
x11-libs/libXfixes:0
x11-libs/libXrandr:0
x11-libs/libXrender:0
x11-libs/libxshmfence:0
x11-libs/libXxf86vm:0