>>721170418
>Battletoads
The only truly hard NES game. Seems impossible at first but then you start realizing most obstacles and enemies in the levels are in the exact same place. So to beat it, you need a lot (a lot) of memorization and good reflexes. The only truly bullshit part is the Rat Race, that requires that you input directions for few frames and it gets harder to do as I get older.

>Super Mario Bros. 1
Lack of lives make it seem the game is hard, but is not that bad, and once you memorize the levels you get better with time. World 8-1 and 8-4 are memorizable (with the sole exception of that one last Hammer Bro. in 8-4, but I try to run under him as he jumps or otherwise just tank a hit), World 8-2 has infinite lives so you can practice that jump until you nail it, and World 8-3 gets easy once you learn where are both powerups so you can kill the on-ground Hammer Bros. with no problem.