You feel compelled to go down...
Smol Dungeon has been out for a year, in that time it's earned about $400.
The game has had two pricing models. For the first nine months it was a paid-up-front game. It was priced at $1.99 (USD). In the first month it earned $252. Over the following eight months I would earn an additional $45 from sales.
In October I switched to a free-to-play pricing model. A lot of other mobile games run ads on their free versions, I decided not to do this. Instead I would offer an optional cosmetic in-app purchase for $2.99.
Switching from paid to free triggered some independent app watching services to post about Smol Dungeon, including on reddit. This got me a nice boost in downloads (in the thousands) compared to when the game was pay-to-play.
Going free earned me an additional $45 in the first month. This was an interesting result. More people than ever were playing Smol Dungeon, 100x more, yet the paid model earned 5x more.
Lot's of plausible explanations for this. The IAP wasn't compelling enough (it's almost entirely cosmetic); the game is too short to justify a purchase after someone downloads it; more folks are willing to pay $1.99 than $2.99; et cetera.
I would guess that my biggest issue is not the details of the IAP, but rather marketing. I don't really do much of it outside the occasional tweet or social media comment. These blog posts are my primary marketing strategy.
Four hundred bucks a year isn't quite enough to quit my day job. Smol Dungeon was about building a complete game from scratch and all the lessons learned along the way, it was not about going full-time indie. That's for the next project!
Happy dungeoning -Kris