If it's for fun, it shouldn't feel like work. While others have some good suggestion, I'm going to ask the hard question: do you really want to be coding as a hobby? The fact that you ask that question suggest you already code enough during work hours and you need to do something else after work. Did you used to code for fun before it was your work? Then maybe it's a good idea to accept that you are not going to find…
The ideal fun coding session would emerge as a byproduct from a particularly successful work-related session. In reality, when coding during times I’m not being paid, I find myself with similar headaches to the workplace.