Yeah, you need to get back on that run you were doing. Don't think I don't know about it just 'cuz I'm new!

Well, I passed through the whole week a few times without any cheat.

Hardest games I have yet to beat (of those I own):

1943
Progress: stage 15, Ryofu, no matter how I've powered up my plane, my skills just aren't up to beating this frickin' stage!

AD&D Dragon Strike
Progress: got as far as the Icewall Fortress.

Adventure Island
Adventure Island 2
Adventure Island 3
Progress: in any of them, no further than the 4th or 5th world.

Adventures of Dino Riki
Progress: got to the final boss several times, but somehow kept failing against it, but mostly those black orbs in some of the stages are what make this game so hard.

Athena
Progress: stage 2, if only the jump height wasn't so random this'd be a rather fun and more playable game.

Battletoads
Progress: stage 9, "Terra Tubes", even with a 1up loop or two here I still couldn't pass it. Volkmire's Inferno, and Intruder Excluder are what really killed my chances though, losing quite a bit of lives on each of those stages. Strangely, while most gamers loath the speeder bike stage, many never being able to pass it, this is my favorite stage in the whole game.

Boulder Dash
Progress: world 6, "Volcano World"

Cobra Triangle
Progress: stage 21, "Reach the Finish", but with moving stalagmites, I wasn't able to.

Darkman
Progress: stage 4-3, "Chinatown", just can't seem to beat this stage.

Dirty Harry
Progress: never got passed the first stage, died somewhere in the sewers making some difficult jumps.

Dragon Power
Progress: stage 9, "The Jungle". Played this during one of the ol' Gamefaqs game challenges several years ago, along with other tough games such as Battletoads, and Cobra Triangle. As with those two, I put up a hell of a struggle, but failed to beat it. Though having plenty of tries available, after a while being sent back to the beginning of stage 7 everytime you die in any stage thereafter gets to be a pain.

Freedom Force
Progress: last stage

Gauntlet
Progress: made it to room 79 with the Valkyrie.

George Foreman's KO Boxing
Progress: got to "Irish" Tommy Morton on the second world circuit.

Ghostbusters 2
Progress: got to the last stage once, I call it a fluke, because I'm lucky to even make it even to the halfway point of the Statue of Liberty stage.

Gyruss
Progress: the furthest I ever got was to Venus.

Home Alone 2
Progress: encountered Harry and Marv inside Kevin's uncle's vacant house currently under renovation, but just couldn't figure out how to pass them.

Hunt for Red October
Progress: got to the stage where you use Captain Ramius, having to disarm bombs aboard the sub, obviously I failed to do it.

Ikari Warriors
Progress: huh...what Progress? Without codes I can't ever see me passing even the first very long, very slow, very annoying stage. I wonder, if they were pit against each other in a foot race, who'd win, Paul (or Vince), or Dr. Jekyll?

Ikari Warriors 2
Progress: much easier than the first game, I think I got to stage 2 or 3 without codes, at least the characters are fast and can strafe in this one.

Indiana Jones and the Temple of Doom
Progress: wasn't sure at first of what I was supposed to be doing exactly, took me a long time to figure out how to even change weapons, but it seems interesting enough. Has seemingly infinite continues, played it for well over an hour, was on level 5, or was it 6, forgot already. Guess you have to rescue every child and find every piece of map(?) in each stage to advance, so it seems. Someday I'm going to tackle this one really seriously, it was kinda fun.

Iron Tank
Progress: quite far, problem was that the password only saves the last checkpoint you were at, not any extra power-ups earned up to that point.

Kid Kool and the Quest for the 7 Wonder Herbs
Progress: got to stage 7-3 once, though I still had a lot of lives, I eventually just gave up, due to being at it all day, I was quite worn out from it. Haven't ever put that much effort into it again.

King's Knight
Progress: last stage with all 4 characters, failed in using the correct magic formation to get passed a barrier.

Kiwi Kraze
Progress: stage 3-something.

The Krion Conquest
Progress: stage 2-3 (damn this game is hard!)

Laser Invasion
Progress: got to the last stage, the Death Star-like corridor leading to the final boss. I did beat it with the 10 lives code, but its never going to be considered official til I can do it with the default lives.

Micro Machines
Progress: 14th race, "Pitfall Pockets"

Mutant Virus
Progress: stage 4, not even sure how to kill the virus in some rooms, sometimes I manage to do so, but most of the time it gets out of control and takes over, one of the most annoyingly difficult games for me that I've tried numerous times to understand so as to play it better, yet to no avail.

P.O.W.
Progress: without codes I can't get very far, stage 2, or 3 at best, but I've also never put much of an effort into it.

Puzznic
Progress: though its been a long time since I last put any effort into this game, 11-5 is the furthest I've gotten on Puzznic, never could figure out this particular puzzle, and I refuse to look at any faqs, or even to skip it via passwords and come back to it after solving the later puzzles. I have beaten, within the first few hours of owning the game, Gravnic, that one was too easy.
 
Rad Racer
Progress: track 6, "Snow White Line" coarse is the furthest that I ever got, and only once.

Rad Racer II
Progress: track 4 I believe is the farthest that I've gotten.

Renegade
Progress: stage 4, the maze...always ran out of time. Its been many years since I've played this game.

Rush 'N Attack
Progress: stage 6 - last boss, only once. I have tried my butt off to beat this game, no way, either just isn' happening or its just not the right time for it to happen.

Sky Shark
Progress: stage 5

Solomon's Key
Progress: unfortunely I don't recall what stage I got to, somewhere close to stage 20.

Solstice
Progress: years ago I mapped the game out on paper, showing locations of items, where to go next, that sorta stuff, solving the game with codes though, I have yet to try it without codes.

Starship Hector
Progress: about mid-way through stage 2.

Super Gloveball
Progress: got to the last boss a couple times.

Time Lord
Progress: stage 5, "Frontline Trenches - 1943 AD", the big soldier boss.

Ultimate Air Combat
Progress: mission 6-2, "Hanger Banger", been stuck on this stage for years, tried it out again last year, still unable to pass it.

The Ultimate Stuntman
Progress: stage 7-4, "Bomb Disposal" puzzle, I got tired from playing it all day and making very slow Progress, so I just gave up once I got to this stage.

Wario's Woods
Progress: game 'A', round 35, game 'B', round 60...never been very good at tetris-style games, can't think quick enough and end up panicking as a result, this is one game that I'll probably never beat.

Young Indiana Jones Chronicles
Progress: level 2-2, "France"

Hardest games that I have beaten:

Adventures of Bayou Billy (a beat'em up where the enemies are faster and more skilled than you, can feel cheap sometimes, so hard to avoid being counter-attacked after every attack you dish out and you have to keep moving)

Air Fortress (beat it once, that last stage took a ton of practice, had to make a map for it as well, just too many passages to remember)

Arkista's Ring (once through is easy, second time, fine, third, crap this is tough, fourth, this is crazy)

Back to the Future 2 & 3 (one of those few games that I needed to make a map for in order to complete it, this is one big ass game)

Batman Returns (without dying, only way to get the best ending)

Battletoads/Double Dragon: The Ultimate Team (beaten it twice, once with a dragon and once with a toad, but its nowhere near as hard as the first Battletoads)

Bill & Ted's Excellent Videogame Adventure (beat it once, took me a long time to understand what to do in this game, and its one of the most frustrating when it comes to looking for stuff, having to jump everywhere)

Bucky O'Hare (one of the more challenging platformers I've ever beaten, they throw just about every kind of platforming challenge at you from Megaman to Battletoads type stuff)

Captain Planet and the Planeteers (only beaten it once, with hundreds of deaths)

Captain Skyhawk (only beaten it once, controls with the jet are just too loose, tending to crash into everything with just the slightest movement)

Castle of Dragon (only beaten it once, you basically have to get through it without dying otherwise you get sent all the way back to the beginning again with the only thing that you get to keep is your experience)

Castlequest (only beaten it once, took me about 2 weeks, without the second controller options, first game that I had to make a map for)

Cobra Command (only beaten it once, hardest thing about this game is the choppy, slow scrolling of the screen)

Code Name: Viper (beat it twice, took me a long time to beat it the first time though)

Conflict (this is one hard strategy game, battles can take upwards of an hour each, but what's worst is all that time wasted if you end up losing, that sucks, took me ages to finish it)

Cybernoid: The Fighting Machine (easy mode only...and certainly was not easy)

Die Hard (beat beginner mode only, once)

Double Dragon (1, 2, and 3)

Ghosts & Goblins (beaten it over a handful of times, but its still among one of the most challenging games on the NES, Red Areemers are nothing, what I hate are the Big Men, Blue Devils, and Ghosts)

Golgo 13: Top Secret Episode (only beaten it once, nearly did a second time but gave up after countless deaths on the final boss)

Golgo 13: The Mafat Conspiracy (beaten it once)

Gradius (only beaten it once, one of the hardest shmups that I've beaten)

Immortal, The (beat it twice total, hated almost every moment of it)

Isolated Warrior (only beaten it once, its a tough shmup/platform combination, and the angled perspective makes it even harder)

Krusty's Fun House (beaten it once, Krusty's controls are overly loose, lots of frustration went along with this one)

Little Nemo the Dream Master (not really hard to beat, but I still lose a ton of lives getting there)

Lone Ranger, The (beaten it once, took me a while to finish it, love all the types of gameplay involved)

Magician (beat it twice, second time with only 1 death, but it was a tough game to figure out at first)

Milon's Secret Castle (beat it twice total, using the continue option)

Mission: Impossible (beat it once, not impossible, but boy was that a hard game from start to finish, everything they could think to throw at you, they did)

Nightmare on Elm Street (tough game, beaten it several times but had a lot of deaths)

Ninja Gaiden (1 & 2, still both are much harder than the third one is for me)

Ninja Crusaders (thank you infinite continues, only ever played and beat it once though)

Robocop 2 (beat it several times, it was crazy hard at first, controls took some getting used to, much like the first Megaman, feels like Robocop is walking on ice, but he's also got difficult momentum to deal with when jumping, but I did get better each game I played)

Roller Games  (a beat 'em up like Double Dragon, but on rollerskates with tons of platforming, bottomless pits and slopes abound, only beaten it once, hundreds of death though)

Silver Surfer (beaten it twice, this one wore my fingers out, I really didn't think I could do it on my own finger speed)

Snake Rattle & Roll (took me nearly two decades to beat it again after my first time, but only because of the last boss, its not one of the really hard games, but still it proved a great challenge the first time)

Solar Jetman: The Hunt for the Golden Warship  (only beaten it once, the varying gravities of each planet made it difficult to adapt, and wtf to the last stage, the game was great up to then)

Star Wars  (only beaten it once, had the hardest time getting past the Tie Fighter battle in the Millenium Falcon, but the whole game overall was tough)

Star Wars: The Empire Strikes Back (use the force Luke...took Jedi powers to beat this game)

Street Fighter 2010 (almost every stage was a boss battle in itself, took a bit to get used to Ken's moves, game sure did keep me on my toes, jumping, backflipping, and climbing all over the place)

Super Pitfall  (only beaten it once)

Swords & Serpents (beat it once, had to map this game out too, surprisingly a very enjoyable experience)

Teenage Mutant Ninja Turtles (1, 2 and 3)

Terminator, The (only beaten it once, didn't have any lives left and only had 1 hit point left, talk about close)

Three Stooges, The (took a lot to get the best ending)

Thrilla's Surfari (only beaten it once)

Tom & Jerry (somehow I had a tough time beating this game for the first time)

Twin Eagle (only beaten it once, had to do it without dying)

Wizards & Warriors 2: Ironsword (gets kinda hard after they take away your chances of continuing, don't help that the amount of damage that enemies do to you is so random, really hate the one hit kills, the elementals at the end on the peak of Icefire Mt. were extremely hard to beat the first time, still kinda tough)

Zen: Intergalactic Ninja (rather difficult but kick ass game with lots of different challenges)

Wow, Miss Clawful. For some of the stuff you've plowed through, a few of the games that give you trouble really surprise me.

I liked Swords & Serpents, as well. It has much better production value than Wizardry on the NES, and despite the dungeons not being as pretty as Might and Magic, it doesn't have to unnavigable outdoor areas, either.

And Air Fortress is one of my all-time favorites, as well. A REALLY underrated game, with a lot of genuine challenge.

TMNT and Ghosts & Goblins always cost me broken controllers hehe

Weird how it works that way huh? Such as Rush'n Attack, probably one of the ones that I've tried the hardest to beat over the years, for me is much harder than most of those games that I have beaten, most of that difficulty stems down to pressing up to jump (so many deaths result in accidentally jumping when I don't intend to), sometimes its simple things like this that make something more difficult than something else.

Eventually though many of those games on my not beaten list will make it onto my beaten list, just a matter of time, mood and commitment. Maybe I should add a little more detail to my lists, as to what makes these games so difficult, afterall, sometimes all it takes is just one or two things to make something harder than it should be.

Miss Clawful, I can't believe you beat Castlequest! That game still gives me nightmares. You can burn the keys in the wrong order and not be able to progress any further. Even with patience, I got stuck numerous times.

Are you using the second controller options? Or playing it like I did, not knowing and going through without trying to mess up?

I only learned of the second controller options here recently after browsing gamefaqs. I haven't tried playing it in years, I was a lot younger when I did. Basically I knew nothing, and had no maps, etc. Though it looked like a cool, it's difficulty level went up dramatically after the first room imo.