One good way to achieve this would be to add a dlopen note
<https://uapi-group.org/specifications/specs/elf_dlopen_metadata/>, and
build-depend on dh-dlopenlibdeps to turn that into a substvar
${dlopen:Depends}. That way, library transitions that rename packages
(like the t64 transition) won't break a hard-coded dependency.
SDL 3 has macros to create dlopen notes, but this is a SDL 2 game. The
macros from SDL 3 could probably be copy/pasted, or there is an
extremely permissively-licensed implementation in src:package-notes.
smcv