People here divided game creation or game entity into two groups:
One claims the idea is what it's all about and the other claims the idea doesn't matter and it's the actual game creation, graphics, logic and execution lever are the ones which makes a good game.
Well, the truth is much more complex. If you don't have an original idea than the pressure start to build up on the level of execution, how well the graphics look and behave, how's the music, how well the game was programmed.
When you have an original idea than it's more easy to win but without good execution your idea will not reach players.
In order to make a fun game you must have maximized all aspects. If your idea is great people will judge you in other aspects. If your idea is not original people will be expecting some new twists on that general idea.
If your idea is great, your graphics are eye popping and your music melts ears your game might not make it if it doesn't have that "magic" thing, that X-factor, that fun factor of playing it.
Bottom line, having new ideas won't help you. If you don't have ideas for future game simple roll a dice. One die will determine the category (shooter, platform, sport, etc.) while the other will determine the time era - futuristic, western, etc.
This method will give you something like: Do a western platform game or even Create a futuristic puzzle game.
With such a direction you can devote yourself to the actual game making. On this skeleton you can (and probably need) more ideas cause with these ideas your game will probably shine. If these small improvement will score in the X-Factor, if these will make people have fun with your game than you have a winner.