3 years is pretty much right when we switched to this new website (April 2014), so I would suggest just starting at the back of the news catalog and reading forwards. Pretty much all major mechanics, from weapons, shields, docking, thrust, AI, armor, factories, planets, and tons of new mechanics like shipyards, passive systems, logic, galaxies, have been changed and added.
Start here and head forwards.
StarMade News - Latest. It's the first page of the new site with an actual game update on it.