I had never joined Steam until they were developing Steam for Linux (which is what I normally run at home). So the first any-OS game I tried was Team Fortress 2. It may be cartoon like and not politically correct, but it is free, runs the Source Half Life 2 engine, and has been popular for many years of updates. Although, to get the best drops or to trade or sell things in the Steam Market you have to buy something (most anything at least once) in the in game Mann Co. Store.
If you think you have done everything in minecraft, you may want to check our the Technic Launcher that as all sorts of modpacks, including Tekkit which is popular. That adds all sorts of machines, mystical things and places, and you can even go to the moon and mars. It has NEI showing in game recipes for most things. http://www.technicpack.net/download