Oh fantastic! I'm very glad to hear that. I'm having trouble following the discussion — is there an obvious way you see that I could re-build the game so it doesn't rely on that depreciated curl option? e.g. recompile a version of Cerberus X with different dependencies or while in an Arch environment?
I would say firstly; I am not a developer. My experience is also not in using ready-made engines; I made a Zelda clone a loooong time ago and made the tile-ing engine for it myself in BASIC. If I could give some advice; I would look at why libcurl-nss was being called and find a more recent/supported alternative to those calls. The developer of the engine would know way more and might be interested in the archlinux thread and use that to tweak their engine and release a new version.
It would require looking at the code before it gets compiled to binary. This of course, is up to you and how much further you want to go. Linux is already a 'niche' platform and Arch users are even smaller group still. It isn't known for being the most user friendly.
Maybe include info in the readme on how to resolve this issue IF that user has the same problem. Overwhelming majority of Linux users actually read those readme files.