How do you get users (and keep them)?

The ideal user is someone who has been building the same thing. It's the guy who's using an excel sheet or wiki to manage their D&D sessions. It's the modders who who have been making fancy, expensive hacks. I personally don't start until I find these communities.

I tried making a grocery price comparison app once. There were tons of these though, and nobody really wanted one. It's just something they'd find useful. So I flipped it, proposed recipes that export into grocery lists. Again, no community. Then I searched around for recipe sharing communities and found one that did low carb diets. I bundled their recipes (with credit) and shared it to a FB group. I got 1000 downloads in the first 24 hours. People on the app kept asking about where they'd get the ingredients. 3% of the app users bought something. So it worked out and ended up a business for over a year.

Even if this doesn't work out exactly, I would say it's easier to start with the sales channel, and then work backwards. If you're making a game, figure out what kind of screenshots or name would make people want to try it.

90% of all of that is just having a great product that is better then any other solution. Rest is details.

#1 Consider searching for "sell the sizzle" #2 Never forget who pays your wage; your clients. #3 The Pareto principle is often important ... https://en.wikipedia.org/wiki/Pareto_principle