1. Pac Man; Atari 2600
2. If you count "flipping the counter" on the original 8-bit systems like the 2600, Yar's Revenge. Otherwise SMB1.
3. ActRaiser
4. SNES
5. 7th Saga (Stayed up three days in a row, only stopping for the obligatory pump'n'dump breaks, eating whilr playing. I beat this in the span of the original 3 day rental period from Blockbuster using Lux and Esuna. Most other games I beat in less than a few hours (examples: Zelda 2 [6 hours], SMB3 [
2 hours ], Ninja Gaiden 1, 2, 3 [3, 4, 7 hours respectively]
Special Achievement: On a whim I hooked my NES up to my stereo in my room, fired up Castlevania 2: Simon's Quest, and entered my password. I then proceeded to turn off the TV leaving the stereo on. Using memory only (and a lot of deaths at the rivers with moving blocks), I beat the game using the final password I obtained during my normal play, utlizing sound only as a navigation tool. I dare you to try this.
Edit: The "achievement" was done back in '90 when there was no such thing as an NES emulator or internet for strat guides.
And goddamn typing with broken finger sucks goat nads...have to edit my life away.