https://bugs.winehq.org/show_bug.cgi?id=14939
--- Comment #40 from Alec Teal alec.teal@gmail.com --- (In reply to Sebastian Lackner from comment #39)
Patch was added to Wine-Staging:
https://github.com/wine-compholio/wine-staging/tree/master/patches/wined3d- DXTn (needs 'autoreconf -f' and 32-bit libtxc-s2tc to be present at ./configure time)
It might be a bit slower than directly implementing DXTn support in Wine, but is a bit more safe from a legal perspective.
Please do not give up on this! I'd love to play this game!