This article is a list of the most difficult, and/or competitive single player games with legitimate scoring systems. By a competitive game I mean a game with a high skill cap and well balanced, legitimate scoring system by which skilled players can measure themselves with on a leaderboard. By legitimate scoring system, I mean a scoring system that cannot be undermined by stat grinding, save/reload abuse, 'in game pre-order/collectors edition bonuses', or anything that causes the playing field to become uneven or unfair between players.

This list does not contain games with repetitive, grinding, unbalanced, skill-less, or unfair difficulty. It also has no 'player defined' challenges, meaning player choices that the game makes no distinction between.

Finally, don't pretend you'd be able to complete these challenges or compete in the high score lists 'if you had no life' - you need skill in addition to practice.

Some genres (FPS, Fighters, Driving, etc.) are built for multiplayer and aren't mentioned here because the AI usually makes a poor opponent. Some of the most competitive/high skill cap multiplayer games are already famous with large tournaments and audiences - Street Fighter, Counterstrike, Starcraft, etc. Difficult single player games are less well known so this list is dedicated to them.

If you think I've missed something, feel free to let me know, and I will likely update this list. I don't have a lot of experience with some of the of genres listed here so I welcome your advice if you are a skilled and knowledgeable gamer. You can expect this post to be edited over time.


Shoot-em-ups, Shmups:

Good shoot em ups follow the formula of complex but fair bullet patterns, intricate skill based scoring systems, auto adjusting rank-based difficulty, and extra challenges for the top 5-10% of skilled players who can complete the game on 1 credit, such as a 2nd loop or a true last boss. Even one bullet connecting with your ship is the kiss of death, so precise movement is vital. Shoot em ups are competitive by nature, due to their nearly limitless skill caps, open ended high scores and the fact that playing a 'perfectly scored' game is often beyond the reach of even the best players. In other words, there's always room for improvement!

Aside from the Cave games listed below that are both difficult to 1cc and score on, there are some games that are not as difficult to 1cc with a low score, but still difficult to get a top score on, like Ikaruga or Espgaluda II.

Mushihimesama Futari 1.5 (Ultra Mode). Available for X360 region free.
http://www.youtube.com/watch?v=ZKYxM1WRvL8 (stage 5 ultra)
http://www.youtube.com/watch?v=0VY-qcGgaCU (stage 5 ultra boss/tlb)

Dodonpachi Dai-ou-jou (2nd loop)
http://www.youtube.com/watch?v=FtFkpldJSpY (original daioujou)
http://www.youtube.com/watch?v=B_ah2ah2QaA (black label version)

Ketsui (ura loop)
http://www.youtube.com/watch?v=X9Rlj6jMOC0 Stage 2-4 ura loop (aka special round)
http://www.youtube.com/watch?v=jKWXubTH5jA Stage 2-5 ura loop (aka special round) and true last boss

Death Smiles Black Label (999 mode)
http://www.youtube.com/watch?v=aEwicCLPwxM

Mushihimesama (Ultra Mode)
http://www.youtube.com/watch?v=PP-mePr1-ZQ


Gun/Shooting Games:

I don't have a lot of experience with this genre. Probably missing some things.

The House of the Dead Series (top ranking, 1cc, etc.).
http://www.youtube.com/watch?v=LJcDONBWaQc

Sin & Punishment 2. Not exactly difficult, but it has a good scoring system and even a bit of 'bullet hell'.
http://www.youtube.com/watch?v=wTgiBx1NqcI



Action/Adventure:

The most difficult games in this genre are the ones heavy on action and light on adventure. This sub-genre of action/adventure started with the release of Devil May Cry and continued on to Ninja Gaiden and Bayonetta thus far. These extreme action/fighters can be compared to playing a single player 'street fighter'. The precise frame-by-frame combat mechanics, deep combo system, unpredictable enemies, extra mission modes, and competitive scoring system make for a very skill based experience. Hideki Kamiya (DMC, Bayonetta, Viewtiful Joe, God Hand) and Tomonobu Itagaki (Ninja Gaiden) are the two heavyweight developers in this genre.

Ninja Gaiden Black/Sigma (Master Ninja Mode). Apparently Black is slightly harder than Sigma.

Ninja Gaiden II for Xbox 360 story and mission modes (Master Ninja difficulty).
http://www.youtube.com/user/kumarab123#g/u

Devil May Cry 1,3 (Dante Must Die Mode w/ all SS ranks).
Devil May Cry 4 (Dante Must Die Mode w/ all SSS ranks).
http://www.youtube.com/user/evf02d

Bayonetta (Non-Stop Infinite Climax Mode w/ all PP medals).
http://zoome.jp/nekopunch/movie_list

Godhand (Hard mode, no deaths/continues aka no gold subtracted from total at end of stage). This game isn't as difficult as the others unless you go with a player defined challenge due to the lack of a real scoring system.
http://www.youtube.com/user/enraiharuka#g/u



Action/Platformer:

Platformers require coordination and skill, but are generally less heavy on combat and more about timing jumps and avoiding environmental hazards. This is one of the most nostalgia-tainted genres due to the overabundance of platformers the NES. Old NES games like Battletoads, Zelda 2, Mega Man, etc. are easy compared to what's out there now.

Interestingly, the most hair-pullingly difficult platformers are mostly amateur productions or ROM hacks like Kaizo Mario World. See link below:
http://www.dsultimate.net/Board/upload/blog.php?b=1113 Platform Hell and Video Game Difficulty; A History

SMW2: Yoshi's Island (perfect 100 scores on every level)

Klonoa 2 (dreamstone collecting, secret levels. etc.. maybe!)

Viewtiful Joe 1 and 2 (all perfect scores, hardest difficulty)



Pinball:

Pinball games are still around and still hardcore with solid mechanics, 'one credit only' play, scoring systems, trick shots, and wizard modes. The wizard mode is usually activated when the player completes all of the normal scoring modes/minigames/events on one credit. There are still annual pinball tourneys held across the world with fierce competition.

The Simpsons Pinball Party (wizard mode)
http://pinball.wikia.com/wiki/The_Simpsons_Pinball_Party
One of the most complex and in depth modern pinball games. "The Simpsons Pinball Party is famous for its extremely hard-to-reach wizard mode, the Super Duper Mega Extreme Wizard Mode. There are very few players in the world who have reached it. Even some of the world's best have failed to accomplish it."

Lord of the Rings Pinball (wizard mode)
http://en.wikipedia.org/wiki/The_Lord_of_the_Rings_%28pinball%29
"The wizard mode (Valinor Multiball) is said to be one of the hardest to reach to date (only being topped by The Simpsons Pinball Party)".



Rhythm:

Guitar Hero Series
http://www.youtube.com/watch?v=-XjaImfQK6U
This popular rhythm game features some extremely difficult challenges that few players in the world have mastered.

Beatmania IIDX Series
http://www.youtube.com/watch?v=Ih-WpTZcFIQ
A DJ based rhythm game that defines finger-twisting agony. Some of the most difficult tracks will have you wondering whether the players have grown an extra finger or three. Honorable mention to Pop 'n Music.

In The Groove Series
A 4-8 panel dance game with challenges far and beyond your usual romp on a treadmill or DDR pad. Unfortunately it turns out such expert play is bad for your knees with all the endless stomping.

Pump It Up Series
A 5-10 panel dance game with challenges far and beyond your usual romp on a treadmill or DDR pad. Unfortunately it turns out such expert play is bad for your knees with all the endless stomping.




Puzzle:

I don't have a lot of experience with this genre. Probably missing some things.

Good puzzle games have simple yet difficult to master mechanics, with solid and balanced scoring systems. They have nearly limitless skill caps due to added stress factors like time limits. Some complex puzzle games may leave your brain tied in a knot.

Tetris: The Grand Master 3 and 4. Sure you've played tetris, but have you cleared Tetris: The Grand Master 3?
http://www.youtube.com/watch?v=jwC544Z37qo

Puzzle Bobble/Bust-A-Move.

Lumines.

Super Monkey Ball (Master levels on one credit aka no continues).
http://www.youtube.com/watch?v=V3XSOjlipQA



Simulation:

I don't have a lot of experience with this genre. Probably missing some things.

Ace Combat 4,5,Zero,6 (Ace or Ace of Aces difficulty, S ranks).

The Sky Crawlers: Innocent Aces (Ace difficulty, S ranks).



Role Playing/SRPGs/Turn Based Tactics/Turn Based Simulation or Strategy aka pseudo-puzzle games:

Most turn based games are primarily puzzle games and their difficulty is in figuring out an optimal solution or strategy within the games mechanics. Almost all RPGs/SRPGs have some easy way to bypass that difficulty through stat grinding, save/reload abuse, or imbalanced game mechanics. No traditional RPG has a useful scoring/ranking systems that penalizes grinding or poor play, making skill differentiation impossible. This makes the RPG genre highly casual since anyone with enough patience can complete one, but it's useless for measuring skill.

If there are action elements they are likely to be very mild and forgiving. Action RPGs (Star Ocean, Tales of X, etc.) tend to be button mashers with little difficulty or depth compared to action games like Ninja Gaiden II or Bayonetta. And MMORPGs practically redefined mindless grinding.

SRPGs or Turn Based Strategy/Tactics games tend to fare better due to the added complexity of many units on the field at once, but again imbalanced mechanics, save/reload abuse, and allowance of stat grinding usually ruin any sense of legitimate challenge. However there are a number of SRPGs with solid score/rank systems that are not easily abusable.


Strategy Role Playing Games (SRPG):
Super Robot Taisen Z (EX-Hard all skill points on every mission).

Fire Emblem: Thracia 776 (SSS rank).
http://www.youtube.com/watch?v=Z3yIek8rNGU&feature=PlayList&p=D1775AF8C2291864&playnext_from=PL&index=0&playnext=1

Knights in the Nightmare (all SSS ranks).

Fire Emblem: Souen no Kiseki - (Mania Mode Fixed Growth).

Fire Emblem: Rekka no Ken - (Hard mode S rank.. highest grade on all ranks).

Elven Legacy + all 3 expansions - (Gold medals on every mission on Hard difficulty).


Turn Based Strategy/Tactics (TBS):
Advance Wars Advance Campaign (all S-ranks on every mission).
http://www.awrevival.netfirms.com/ac/m11/m11.htm
http://www.awrevival.netfirms.com/ac/m6b/m6b.htm
http://www.awrevival.netfirms.com/ac/rivals/rivals.htm

Panzer Tactics (all secondary objectives/highest rank on every mission).

R-Type Command (a fairly complex SRPG with a scoring system.. too bad, since almost nobody bought the game)


Dungeon Crawlers/roguelikes:
ADOM, Nethack, Crawl, other modern PC roguelikes.

Wizardry IV: Return of Werdna.
http://en.wikipedia.org/wiki/The_Return_of_Werdna#Difficulty

Wizardry 8 (Ironman mode). In Ironman mode you cannot save/load.


Strategy Games:
Civilization 4. Incredibly complicated game with multiple difficulties and a scoring system.

Good SRPGs that were unfairly reviewed:
These are not necessarily difficult games, but good SRPGs that were unfairly rated by clueless/skill-less reviewers.

Front Mission 4, Panzer Tactics, R-Type Command, Valkyrie Profile: Covenant of the Plume, Rondo of Swords.