I love reading that you'd never used Fennel before the jam; that's so cool that you could pick it up quickly and still finish your game with 2 days to spare.
I pushed some changes to fennel-mode to get rid of byte-compiler errors; can you let me know if that fixes the indentation problems you were seeing?
https://gitlab.com/technomancy/fennel-mode/commit/e36c48a0ce7045ea604fb3159c312d...
I think it was missing an explicit require of lisp-mode?