Idea for NES game?

I've started programming NES games in 6502, but I want an idea for a game. The obvious is pong.

Any suggestions? And keep it simple, the NES is complex despite how under powered it is.

How about you make a blue robot who travels through the land defeating other robots and stopping an evil scientist?

... Oh Wait

Was the sarcasm really necessary?

Gyromite 2. My ROB needs some love

How about "Die Hard: With A-me A-Mario, AND SOME VENGANCE!"

International Terrorists in the form of Bowser and the Koopa Troopas have taken over Delfino plaza and Captured The Princesses Daisy and Peach, Toad, the other coloured toads, those weird fat things from Mario Sunshine. and that weird old brown Toad guy.

And Mario is caught up in all this shit whilst Luigi, the lowly coast guard, gives him support via radio from a coast guard boat just off the beach. All the while the Media and FBI are being right pricks about the whole thing, and Mario and Luigi are getting rate pissed off.

Mario kicks ass, takes names, and blows the shit outta all the bad guys. And, naturally, saves the day.

Bioshock - THE 2D!

I actually quite like the Bioshock game idea...