A game I'm working on at the moment is one I started on 11 years ago, I obviously shouldn't feel so bad :) Though in my defence:
* That hasn't been a continuous period or anywhere near that, with months to years of breaks, and I've started and completed other games in the meantime.
* The game has been in a playable state for years, it's more that I'm returning to it to add some improvements (trying to improve the graphics from free sources - OpenGameArt didn't exist years ago; taking advantage of new APIs, i.e., SDL 2; adding some things like a test suite, which I now know are very important, but didn't when I set out 11 years ago).
A lot of Open Source games are under development for much longer periods of time, though again, it's more that they're playable early on, and people continue to develop them afterwards for years. It's unclear whether this was the case with this game - and he just didn't release until he decided it was "finished" - or whether it really wasn't playable until he released it.
I'm more interested though in this as a story about marketing rather than game development (for which there are countless journals people can read here on Gamedev). He does appear to be lucky to get some free publicity. On the one hand finishing a game is an achievement no matter how long it takes, most aspiring individual game developers probably don't get that far. OTOH, "person finishes a game!" shouldn't be news. This wasn't a game that time forgot - this was a game no one else knew about it until he released it (though people may well forget about it with time...). I suppose it does demonstrate how some marketing can be achieved - not just releasing a game, but having a video/etc documenting something about the process.
As a more general question - how good have people found things like YouTube for publicity, either putting videos of gameplay, or trailers, or development-story type things? Is it a great way to get publicity (as he seems to have), or is 300,000 a case of hitting it lucky? (Though admittedly, 300,000 YouTube views probably doesn't translate into anywhere near 300,000 downloads.)