If someone gets aborts without opening the Tanglewood gaiming window with strange
OpenGL driver paths like the following message (here for AMD Radeon RX 5700 XT / Navi 10 / RDNA1):
  libGL error: MESA-LOADER: failed to open radeonsi (search paths /usr/lib/x86_64-linux-gnu/dri:\$${ORIGIN}/dri:/usr/lib/dri)
  libGL error: failed to load driver: radeonsi
  libGL error: MESA-LOADER: failed to open radeonsi (search paths /usr/lib/x86_64-linux-gnu/dri:\$${ORIGIN}/dri:/usr/lib/dri)
  libGL error: failed to load driver: radeonsi
  libGL error: MESA-LOADER: failed to open swrast (search paths /usr/lib/x86_64-linux-gnu/dri:\$${ORIGIN}/dri:/usr/lib/dri)
  libGL error: failed to load driver: swrast
  Could not create OpenGL context
  Segmentation fault
one can solve this by moving the file "libstdc++.so.6" from "<GOG_INSTDIR>/game/linux" e.g. to new sub-
directory `Tanglewood_Test' - so that the C++ Standard Library of the current GNU/Linux system is used.
This was a hint of the Devs and worked for me on Kubuntu 20.04 LTS (Focal), 19.10 STS (Eoan) and
Kubuntu 18.04 LTS (Bionic).
Further remarks will be put below when available.

JMB

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??.10.2020: ... to be continued ...