The funny thing about ideas in game design is unlike many other forms of entertainment, that other people usually won't take other people's because they already have their own. You sure there's absolutely nothing you can think of? If not, here's a little something that's been in the back of my mind for some time that I'll likely never get around to doing:
In the future, you are an obsolete robot, and like with most technology, when it's obsolete, it gets thrown away, upgraded, or deactivated. However, this particular robot escapes the grasp of its owners in light of learning it was about to be "Decomissioned". However, the robot has pursuers, who are experts on hunting down rogue units. You are deemed a threat to society, and your only objective is to survive, and make your way out of a futuristic city.
The gameplay is up to you, but I envisioned it as being very tech based. Since you play as an obsolete robot, when you attack, you lose energy. The only way to gain energy is finding power cells. The energy also keeps you alive. It's somewhat similar to the mechanic of energy in the F-zero series. You can use attacks, but it also drains your life, so you have to be careful. Other ideas I had were being able to detach the robot's body parts to complete puzzles. A bit like how Bender from Futurama can crawl around using nothing but one of his detatched arms.
The final boss could be your hunters, or perhaps your former owners.
Not a very developed idea, but maybe it'll catch your interest.