I'm an old school gamer that's fallen out of the habit.
I have two favorite settings.
One- The old Element Masters gameworld (company forgotten) was a great world, maybe due to a sharp witted GM. Elf, human, dwarf and halfbreeds all hoping to stop a common invader. Plus the Half-Trons. Trons were the supper-sized genderless minions of the invader's shock troops. Born full sized from captured women, killing mom in the proccess. Half-Trons are from mothers that escape before the kid is big enough to be programmed (we hope) Incomplete, male, and grown to full thinking size in the last hour, with some of their mom's memories up to the last second of life.
In that world there's an invation into your magical world from forces of high tech power and some incidental other thingys get in too. You players are tapped by a great trainer to learn the lost art of Elemental Manipulation. THE most poweful form of magic. (It was lost when the other masters lept into the other demention to fight and the remainders were assasinated.)
My character, dwarven, lost an arm and foot to take out a great three headed dragon guarding a portal. The hand was replaced with robot parts and dragon armor.
When we got to the end of the set cenario and literally blew the invading extradementional bad guy off the planet we kept playing.
The other Favorite Gameworld is R.I.F.T.S. due to it's versitility and "it's all inside" element.
RPH