Back from hiatus - what did I miss?

I stopped playing chess around this time last year, mostly because I could not find anyone nearby who played chess.

Anyway, I want to get back into chess, primarily online chess, which I am starting to miss.  Were there any major developments or theoretical breakthroughs that occurred in chess since around April 2014?

Also, what would be the best way to get back into chess?  When I left off, I had just built an opening repertoire and studied positional play (I read Nimzowitsch and then John Watson).  I am a Class C player and have been playing on and off for around 7 years now.  I am thinking of getting back into chess by studying intermediate tactics, which is something I am only so-so in.  Your thoughts?

One thing you missed. Standard ratings were adjusted. Your rating went from 1025 to 1175 without your having to play a single game!