It's not that there aren't any new ideas, it's that publishers aren't willing to take risks on new, untested game ideas when development costs are so high.
The reason that the indie game circles are so much more exciting and characterized by a much higher degree of originality is because they only have shoestring budgets to risk; they're a lot more agile, and a lot more willing to stray away from the standard formulas.
Sure, there are one or two mainstream releases every few months that are original or interesting, but for every Mirror's Edge there's six Maddens, two Halo clones, and three wholly unremarkable RTS games.
The reason that the indie game circles are so much more exciting and characterized by a much higher degree of originality is because they only have shoestring budgets to risk; they're a lot more agile, and a lot more willing to stray away from the standard formulas.
Sure, there are one or two mainstream releases every few months that are original or interesting, but for every Mirror's Edge there's six Maddens, two Halo clones, and three wholly unremarkable RTS games.