Possibly the hardest game I've ever played...

64-Bit Nintendo Machine

64 Bits of Power!
The Japanese version of NES Open Tournament Golf is very difficult. Unlike the North American version, the goal is to finish all five courses. There are no tournaments, Steve and Mark are absent and the game is harder.

Here's why it's hard:
1. Scoring limits: In order to finish a course, you'll have to score under the limit. Should you go over, you'll have to restart the course from the beginning.
The limits are: 18 for Japan, 12 for Australia, 8 for France, 4 for Hawaii, and 2 for England.
2. Downright NASTY course design: Some holes take into account extreme precision, long hole length, and astronomical luck. Hole#10 of England is a good example: You'll have to hit the ball across the water to reach the green, go too short and you fall in the water, go too long and you fall in the water. Coupled with the score limits means that one mistake can fuck up the entire run faster than you can say "Oh".

All in all, the Japanese version of NES Open Golf is only recommended if you've had intensive practice with golf games.
 
Super Mario Bros.: The Lost Levels - While I haven't played the original, I have played it in Super Mario Bros. Deluxe, and the levels are really frustrating. I had to use restore points all the time, and sometimes, I just got stuck cause I had no idea what to do. It feels like these levels weren't even made by Nintendo because of how hard the levels are and how similar the game is to the original Super Mario Bros. It kinda feels like a kaizo version.
 
Personally, Geometry Dash is extremely tough because it resulted in the most troublesome aspects of an autorunner and a rhythm game. Its death system is more reminiscent to an endless runner where getting hit once is a cause for repeating the whole thing, and worse: the game is designed to have zero checkpoints. The rhythm aspect means that the level is based around the music played, but the game has a lot of different elements so it's not easy to keep track of the complexity in one level. It's one of the few games that I completely gave up on because completing the game-given levels is just not worth the trouble.

Thank you for reading.
 
Personally, Geometry Dash is extremely tough because it resulted in the most troublesome aspects of an autorunner and a rhythm game. Its death system is more reminiscent to an endless runner where getting hit once is a cause for repeating the whole thing, and worse: the game is designed to have zero checkpoints. The rhythm aspect means that the level is based around the music played, but the game has a lot of different elements so it's not easy to keep track of the complexity in one level. It's one of the few games that I completely gave up on because completing the game-given levels is just not worth the trouble.

Thank you for reading.

I actually did beat all base game levels in GD, and they're actually not that hard by the standards of an average player of today, funnily enough. Not easily winnable but far from extremely hard and near impossible.
 
Crash Bandicoot 1-3: I've only played the N-Sane Trilogy versions of these games and they're quite hard.

I have managed to collect all but four of the clear gems in CB2, I've cleared up to Lights Out in CB1, and I'm working on 3.
 
100%ing Sonic & All-Stars Transformed is as hard as nails. One of the harder racing games I've played.
 
I actually did beat all base game levels in GD, and they're actually not that hard by the standards of an average player of today, funnily enough. Not easily winnable but far from extremely hard and near impossible.
I figured that if I invested more time into it I might be better at it, but the thing is, I am not in a mood for devoting time to just one game to beat every level since this is not the only game I have. I also found getting the three collectibles to be worse because it has to be collected in a completed run to count (although I think you don't have to collect all in one go).

Thank you for reading.