I had the incredible realisation that the font actually appears within the game and not just in the title.

Using this new information, I made
this reference sheet and started making the letters in Inkscape. (It's easier to use than the actual font creation software that I have found. Is there something better than FontForge that is also free?)
Only lower case for now:
The shape of some letters is hard to tell from just the reference sheet. The letters that concern me the most are
j s and
z.