Hi folks - I'm new to the board, so please excuse me if I just jump right in, but I found the topic interesting.
I'd have to agree that most of today's games are just rehashes of retro games, and only rarely does a new game introduce something that really feels innovative. For me, Populous was an example of a game that broke new ground when it first came out, and of course it has spawned plenty of imitators. It's always been easier to implement a good idea than it is to come up with one in the first place. There's nothing wrong with reusing a proven concept of course, but the trick is to do it in such a way that it improves or expands on what has come before instead of merely copying it.
The last game I can think of that really introduced something that seemed novel to me was Messiah on the PC, where your character is an absolute weakling, but has the ability to "possess" the body of any other character he encounters (sometimes drawing a hostile reaction from any witnesses). This have been done before but I'd never seen it, and it kept me from writing off the game as "just another FPS".