A lot of people want to make games but don't know what to make. A lot of people also think of great game ideas but never use them because they don't know what do to with them or don't know how to make them work. Why keep those ideas locked in your head when someone else might love them!
Post any game idea here, and feel free to post as many as you want. No real rules just remember that the less you have to explain, the better. There are no limits! Video games, physical games, mind games, everything is on the table!
I'll start with one I've had for a while and really like but know someone else could do it better than I could:
Animal Crossing but you collect micro games instead of furniture. Compete with your local villagers for highscores.
If you need more examples, @moshboy has a plethora of random game idea tweets.