I'd say that to the end-user it doesn't matter (which is why it's not mentioned on the linked store page), but to the HN crowd it's interesting because lisp is a nifty hacker topic and seeing someone manage to write a game in it is pretty cool.
(It's probably more interesting than all the "X, a clone of Y but in Rust" posts, at least.)
I have a private conspiracy theory that one of the reasons for the recent remaster of The Last of Us is to move all of Naughty Dog's go-forward IP off a Lisp-based workflow. Through at least The Last of Us (2013), ND had been still sneaking in Lisp through the back door: while the engine was in C++, a toolchain in Racket would generate all the entity component types as well as data for various animations, etc. I think there's been a shift in developer talent at ND in the past few years, and Druckmann wants to get rid of all the Racket stuff (because it's hard to find maintainers for it) and stick with a standard C++ workflow.
All of which makes Kandria even more refreshingly welcome.
To my knowledge, Naughty Dog have never fully implemented a game in a Lisp. They used it and custom languages written in Racket as scripting and automation tools.
The game posted here appears to be written in Common Lisp from the engine up.
This is an unnecessarily cynical comment, IMO. The title already establishes the value prop of the project as a "Show" entry; it's an action RPG, i.e. game. It's not "I made a clone of a C tool but in Rust" where there is no actual value prop.
It's a bonus that it's written in something a bit more interesting than your average game.
(It's probably more interesting than all the "X, a clone of Y but in Rust" posts, at least.)