For World Of Warcraft, Minecraft, Skyrim, Spore, And HalfLife 2.
Specs:
Intel® Core™ i5-4200U Processor, (3M Cache, up to 2.60GHz) with Intel® Turbo Boost Technology 2.0
16GB DDR3L 1600MHz (8GB + 8GB)
750GB HDD (5400rpm, Serial ATA)
2GB DDR3 NVIDIA ® GeForce® GT 740M with Optimus™ Technology
Not only is 16 GB enough, it's overkill. You don't need more than 8 GB today with a dedicated graphics card. If you already have 16 GB of RAM, use it. If you're buying the RAM aftermarket, though, it's not worth the extra cash.
Good enough for what you want by today's standards
Nowaday 12g=8+4 good for any hard game but for those kind of game 8g is great
Forget RAM, you need good graphics first (and processor second) for gaming. Any RAM over 4gb is enough.
Your graphic card is very good, processor may be less powerful, but sufficient IMO.
You did not mention your screen resolution, but if you don't have much greater resolution than fullHD(you probably have fullHD) then all games you mentioned will run fluently on full details, maybe except Skyrim, but if you change graphic settings a bit it will run fluently too.
You have so much its excessive lol. You can run anything on that thing, the graphics maxed out. Your graphics card and RAM is prolly the best you can get for gaming. Anything more is a waste of money because you can't tell the difference beyond that.