The most common mistake I see unsuccessful* developers make is treating their apps as products, rather than services.
Now by unsuccessful*, I mean financially. I hate to classify the ability to make money as a success for a game. There are so many games I would classify as successful that don't make any money, and likewise there are games that may make some money (maybe not enough?) that I wouldn't call successful.
Let me try again:
The most common mistake I see unprofitable developers make is treating their apps as products, rather than services.
(ok, better? Let's move on...)
It's a really easy mistake to make. We're used to dealing with software, and well most things, as products. You create it, you release it to the wild, make some amount of money with it, and you move on to the next thing that will make you money. This is still the business model for thousands software products, including many games.
Yet the most
successful profitable games I've seen are not products, they're services. Very much in the independent and mobile spaces. In the new age of digital distribution, users expect updates. Look at your favorite games in the mobile market places, I would bet that most have new updates released in the last month or two, even if the game came out years ago.
Iterating on your game has tons of advantages. Developing your game post release allows to you get real feedback from real players. Not just sample groups or playtesters, but use real-time live analytical data of how users are interacting with your game. Is there a friction point where users don't know what to do, and keep hitting the back or help buttons? Is there a level that has a huge spike in player deaths/quits? Fix those issues, put out a new update. Let the community know that they can contact you, that if there is something they don't like encourage them to message you directly, and then follow through replying to them, fixing the issue and asking them to try again after you've updated. That connection you'll make can turn the stronger hater into your biggest supporter.
It's also great for marketing your game. If I am trying to get a blogger to write about a game I made, but I haven't updated the game in over four months, why would they bother doing so? Obviously I don't care about the game anymore (or so it seems), so why should they? But if I've just added a new feature or level, and then I let the blogger now, I have some value to offer. There is "News" about the game, beyond that it exists. Many reviewers won't bother looking at a game until after it's been iterated on a few times and has built up a community. Don't expect to have a reviewer care about your game if nobody else does.
If you're updating regularly, even if its small tweaks or a new level/feature here and there, it shows that I, the developer, care about the game. I am still working on it, improving it, even if the game is "done" and my priority now is to market/sell it.
Next time you're planning out a game project, make sure you schedule in time and budget for not just pre-release development, but post release development as well. You can never finish polishing a game, it can never be "perfect" at release, so don't plan on it.
Think of the games you make not as products, but services.