I have never played a game so diligently as sota. The simple reason is that it allows RMT (real money trading). I can't recall the last time I played a game purely for fun. It was either to grind for skill points to make my character stronger (dcuo), grind games for a portrait (starcraft 2) or farm gold purely to sell later on (WoW). The last game which i played for story reasons was starcraft 2: legacy of the void. Before that, it grows hazy. Maybe fallout 1 i guess. Way before that was Wasteland and The Bard's Tale. There was also Wing Commander, Civilization and Ultima 6. Note that all these are old single player games which came out before the Internet. When the Internet was relatively new, I was keen on Starcraft.
Recent games which i played to get some cool styles are WoW: Legion (to get Ashbringer for my paladin), and dcuo (to get the Firestorm head style).
The last time I was really hooked on a game was around 2013, when the Home Turf expansion was released for dcuo. I had a blast decorating my base, and posted about it on my blog. Mepps even mentioned my blog on the forums, that resulted in a spike in my blog viewership.