I haven’t really had experience in selling games yet, but here’s my 2c.
Obviously a lot of people are making either some money or a lot of money from indie game development. They must be. It doesn’t just boil down to the fact that you’re going solo, it also depends on your talent, creativity, artistic ability, vision, efficiency, cleverness, marketing know-how, understanding of the audience, etc…
I don’t know of many indie games (not an expert really) that have been huge successes that were done by one person alone, except perhaps for the likes of VVVVVV/SuperHexagon etc. Doing all the code and design and graphics and artwork and music etc yourself can be tuff, especially without any $$$ to put into it. But that doesn’t stop a LOT of people from trying.
From what I’ve heard, the casual games business on desktop (mostly Windows) is still experiencing growth and can be quite lucrative provided you can cater to that audience, which does require a certain level of graphical quality, ease of use, appealing to women somewhat, etc.
Another option is creating tools/assets for everyone ELSE that is trying to compete with you to make successful games. Even if it’s insane to keep making games with no hope of success, people keep trying (for the love of it?), and that’s something you can capitalize on by providing picks and axes for those gold diggers. Again you have to come up with something pretty special/in-demand to make a living off it but it can be supplemental. Part of my strategy at present is making a large number of small and fairly self-contained assets/tools that don’t need much maintenance or support, yet provide genuinely useful services, selling at a fairly low price, and letting those build up as multiple threads of income over time. Some other people take the strategy of making one or two big assets/tools and going from there (I’m trying that too now).
There is also always opportunity of being first-to-market on new platforms, such as the Ouya game console (android based) which comes out next year … when there is a limited supply of games/content on a new platform and lots of people rushing to it you can really capitalize from the profound reduction in competition, or so I hear, because many very early iOs apps made a tonne of money this way even though over time they didn’t prove to be the best of their kind. People are much more willing to overlook shortcomings when the range of offerings are limited, and get much more picky/discerning when there’s a lot to choose from.
As a solo developer like yourself I aim to be very … mmm… clever? … and careful about how I use my time and what kind of projects I take on. You just can’t spend your time doing whatever project you like… many projects just aren’t feasible to do alone, not just because of scope but also if you’re doing things part time (like me) then you need to take on strategies that produce as much game for your time as possible … e.g. procedural level generation perhaps, using pre-existing assets, that kind of thing. Make yourself act like a compression algorithm - you need to squeeze as much productivity/result into as little time as possible, and that means maybe that project with 100 hand-drawn levels is out of the question.
There absolutely is money to be made as a solo indie and you CAN do it but only with the talent, ability, foresight, innovation, risk-taking, and perhaps some luck. Experiment with something small, test the waters, see what sticks and takes on a life of its own, because ultimately you do not know exactly what’s going to work - there’s probably nobody here who really really really KNOWS an exact formula for gaming success.
I have noticed thought, lately, that while there has been a lot of ongoing growth in casual/easy games, there is also now a trend forming toward hard games… VVVVVV/SuperHexagon being examples, games which really test your abilities and provide a lot of challenge/difficulty … actually can make for much more interesting gameplay. Also casual games are shifting to what they’re calling mid-core ie not just totally wishy-washy easy but somewhat more challenging (but not hard-core). … and while that’s happening the previous mid-core crowd are maybe shifting more to hard-core difficult games, which is perhaps why tuffer games are making more of a comeback. Make something that’s really challenging - it seems to give a game more of a reputation.