Did I mention I have a working NES?
Bwa ha ha, I have 3, and ones a top loader
I've also got 450+ games, none of which are ROMs. People ask why not just download them...its more fun to collect, especially the rare ones :)
I've never felt like you can have one game as the greatest ever, because when you deal with genres its like comparing apples to oranges to swords to...TVs...you get the idea. Heres some great ones, each a little different.
Super Tecmo Bowl - Best pigskin game there was, although the 100 yard passing was a little unrealistic. Still a great game, can't go wrong with Da Bears or San Fran.
Punch Out - Ruled the boxing games, loved hitting certain bosses with a power punch at the right time to put them down ( see 2nd fight ).
Base Wars - Greatest. Baseball game. Ever. Robots, weapons, baseball...it was awesome. There was nothing sweeter than stealing a base, finding your opponent at 2nd with the ball, then fighting to the death to see if you're out or not. Fun game for 2 players.
River City Ransom - Great game for 2 players. Beat up thugs, take their lunch money, use it to buy cool upgrades like super fast Dragon Feet.
Super Dodge Ball - Another good sports game, and the teams certainly were diverse. I loved taking India ( think it was India ) and using the character "Swami" on my team. That boy could take more hits than a Terminator, frustrates my buddies all the time.
Tengen Tetris - Very rare Tetris game released by a 3rd party ( they used to have the black cart games with a slant to them ). The music was better in this game than Nintendo's version, plus they had a 2 player mode where you had to work together on one screen...one person moves a piece, the other flips it.
Super Glove Ball - Great for groups of people, and besides...you had to have some game you knew worked with a Power Glove, heh heh.
World Class Track Meet - See above, except with a Power Pad. What people played novelty-wise if they didn't have a Power Glove.
Metal Gear - A cool shooter game where you could switch your gravity at will, which also introduced a puzzle-like atmosphere.
Contra - Nuff said. Beating it using the old Konami code is one thing, beating it without the code and no continues is more fun
Castlevania II: Simon's Quest - Best Castlevania for NES IMO, and really launched the series which is still going. Flame whips are sweet.
Teenage Mutant Ninja Turtles II - An arcade classic that was also fun to play at home.
Super Mario 3 - Nuff said.
Legend of Zelda - As far as Adventure/RPGs go, this one is a classic and started it all for the series. I have a fond place in my heart for the original Dragon Warrior, but Zelda was a better game. The sequel to Zelda was also pretty fun.