So, my game's been on the iTunes store for a week now and I've gotten 630 downloads. I accidentally messed up the code to display ads in my game, so unfortunately, I have no idea what kind of money it could be making. I submitted a patch Sunday to fix this, but it looks like there's an average of 6 day wait for a new app or patch release. Doing some research, my guess would be under 10 cents a day at this point in time (I have an over/under bet with my friend at 5 cents). This is obviously not FIRE material, but any positive revenue is good I guess. I also added a lot of new content to my game last week which is showing up in patch 1 which adds a lot of replayability to my game.
That got me thinking about supplemental income in general and how it affects FIRE. The marginal increase in savings can be dramatically different from the marginal increase in income with supplemental sources. For example, if a household makes $6k a month and has expenses of $5k, they're putting $1k toward reaching FIRE (one would hope). If they get a side business and bring in another $1k a month, while that is only a ~16% increase in household revenue, it is doubling their savings rate. Obviously, this hypothetical couple might not be too mustachian to begin with and it might be easier to just trim another $1k from their budget, but I'm just trying to show the numbers here. Imagine how much they could increase their savings rate by attacking it from both angles.
I guess I'm trying to say that hobbies that have the potential to bring in small amounts of money may have a much more meaningful impact on retirement savings than is initially apparent. If you've got a hobby that you can monetize by even a small amount, without detracting from the enjoyment of that hobby, it might be worth taking a look at.
If anyone's interested, I'll keep you updated with my stats on downloads and how much my game brings in. Come on 10 cents!