Most games are developed, a bit of effort/money directed on promotion/marketing, dropped, and then onto the next project. So I think these numbers are more of a reflection of developer than consumer trends. Games that are developed in a different way often show [very] different trends. One of the most extreme examples I can think of is Kenshi. Its SteamDB [1] numbers are something else! It was made by one guy who worked as a security guard to make ends meet while making it.
Of course making games has to be a labor of love though. I mean the guy had double digit player counts for years, and sales likely reflective of that (if not worse), while he continued to keep developing a game that he was clearly building for himself at least as much as for "the market."
And as for Dwarf Fortress, it's kind of in a mixed zone, because it got the sort of big marketing/promotion push that's usually reserved for "fire it and forget it" type titles, and the consequent drop in players it entails as you ended up doing things like attracting players who thought they were buying 'The Sims - Ultra Detailed Dwarven Edition With Retro Graphics' and quit after 30 minutes. But I really don't think that's the developer's plan. So I suppose we'll see!
As indie game dev myself I totally agree with you, but while DF is special it still had usual marketing compaign and that big release date. My guess it will likely perform even worse than projection since a lot of people who played DF for years bought it more like a donation. E.g more of people who bought it wont actually play it much and game will game less of natural social marketing out of these sales.
Again I not saying that Toady gonna abandon the game, but sales will go down in coming months and it's very unlikely that in coming years they'll get another $7M of sales in one month.
Of course making games has to be a labor of love though. I mean the guy had double digit player counts for years, and sales likely reflective of that (if not worse), while he continued to keep developing a game that he was clearly building for himself at least as much as for "the market."
And as for Dwarf Fortress, it's kind of in a mixed zone, because it got the sort of big marketing/promotion push that's usually reserved for "fire it and forget it" type titles, and the consequent drop in players it entails as you ended up doing things like attracting players who thought they were buying 'The Sims - Ultra Detailed Dwarven Edition With Retro Graphics' and quit after 30 minutes. But I really don't think that's the developer's plan. So I suppose we'll see!