I was reading the Din's Legacy manual today, and noticed this section:
S3/DXTCTexture Compression on Linux
sudo apt-get install libtxc-dxtn-s2tc0
I wasn't sure if this was something I needed to enable on my system, so I looked into. It seems, that the patent expired so dxt/s3 support is now rolled fully into Mesa (as of version 17.3.0). So it should no longer be necessary to get the aforementioned library, from that release and newer.
From the mesa faq ( https://www.mesa3d.org/faq.html
4.3 Why isn't GL_EXT_texture_compression_s3tc implemented in Mesa?
Oh but it is! Prior to 2nd October 2017, the Mesa project did not include s3tc support due to intellectual property (IP) and/or patent issues around the s3tc algorithm.
As of Mesa 17.3.0, Mesa now officially supports s3tc, as the patent has expired.
In versions prior to this, a 3rd party plug-in library was required.
Just thought I'd share, and also it's been great to still be able to play these games since dropping windows, so thank you so much for the linux support.