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It looks like you're not missing any libraries that urw is trying to load, so something else is wrong. It's working for me on Manjaro.
The root cause looks to be here:
https://wiki.libsdl.org/SDL2/SDL_RWseekSDL_RWseek() is actually a wrapper function that calls the SDL_RWops's seek method appropriately, to simplify application development.
Prior to SDL 2.0.10, this function was a macro.
So my guess is that the game is expecting SDL >= 2.0.10 and you have SDL < 2.0.10, or visa versa.
I did some googling, and found someone who was having this issue, but for a different game, ADOM, and there's a reply there saying that someone on Mint was able to get it to work after following the instructions there:
https://www.gog.com/forum/adom_ancient_domains_of_mystery/problem_launching_version_334_on_ubuntu_2004 -- I'd be cautious about downloading anything from some random user's github -- instead download the libs from a trusted linux repository to the game directory and then adding them to the $LD_LIBRARY_PATH shell variable sounds promising.
https://www.gog.com/forum/adom_ancient_domains_of_mystery/problem_launching_version_334_on_ubuntu_2004/page1Since Mint is Debian based, an Ubuntu or Debian version of the library should be okay.
I'm not sure how the steam version works exactly, probably the files are in different locations than on my computer but the way of working should be the same:
file $(which urw)
/usr/bin/urw: Bourne-Again shell script, ASCII text executable
file $(which urw3-bin)
/usr/bin/urw3-bin: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=de4cf685333bb53e3cda57c9ee122573ce947471, for GNU/Linux 4.4.0, stripped
so /usr/bin/urw is the shell script which sets stuff up and then launches the binary, so you can edit it to add some more setup, and that's where you'd add the path with the libraries you downlodaed to LD_LIBRARY_PATH.