"There is nothing new under the sun". But you can borrow techniques, do mashups, combine in new ways. That's not pure innovation but it can result in good games.

Innovation is highly overrated. "Innovation" depends heavily on what you're used to, what you've seen before. Some people might have thought Stratego was innovative when it came out after WW II, but in fact it derives from and is almost identical to a game on the market in Britain since 1909 (L'Attaque). Yet even today, Stratego will be "innovative" to someone who has never encountered that kind of game before.

I discuss "Innovation in Game Design" in this blog post: http://gamasutra.com/blogs/edit/blog/item/90787/index.php

What many people really want from a game is not innovation but surprise. I think surprise can come from how you do things, what elements you put together, how you model something - from many things other than innovation.

Also see "We need to get over innovation": gamasutra.com/blogs/TomBattey/20140129/209583/We_Need_to_Get_Over_Innovation.php?