This seems like the kind of thing that might draw more interest via Patreon than purchases, especially with the promise of semi-regular updates to keep some buzz going around about "the Excel XCOM guy".
Patreon is an interesting idea for projects like this. The issue I have is that Patreon is currently viewed as something where you pay $x/mo and get regular substantial updates (comics, art, etc). I'm not sure OP could deliver enough monthly value to justify a Patreon subscription.
Patreon also has an $X/update model (which you can cap at $Y/mo as a patron if you want), which fits rather nicely for niche products as long as the creator can avoid the perception of padding out updates.