I had that problem last year, I ended up buying JRPGs on Black Friday/Steam Winter sale to play, lol. Basically, I branched out.
Right now, I'm done with my yearly purchase again, but I got some games in the Black Friday sale and already started Stardew Valley and Invisible Inc. Once I get bored of them, I'm stuck with playing my go-to MMOs for dull time (GW2, SWTOR, TESO or The Secret World) or trying to find something interesting in my (un)played backlog. They are unplayed because I usually get those games in bundles and I'm not that interested in them or they are games I played a bit but dropped to play more interesting stuff. I tend to replay older games I like more than reduce my backlog too.
The scary part, next year the only game I'm interested in is MEA which seems to target release in late March (but I might wait, I haven't bought a single ME game on release day). I got a bunch of KS that "should" release in 2017 though.