Gradius Gaiden (グラディウス外伝)
System & Settings: PlayStation 1, Hardest Difficulty
Well, here it is, a 4-loop clear of Gradius Gaiden on real PS1 hardware! I believe Loop 4 is where the game reaches max difficulty. It's similar to loop 3 but there are even more suicide bullets from certain enemies, and they also appear to move faster.
Loop 1: https://www.youtube.com/watch?v=XfNm9O_WiPs
Loop 2: https://www.youtube.com/watch?v=GkVH6gP1W7g
Loop 3: https://www.youtube.com/watch?v=uosii0j0MA4
Loop 5: https://www.youtube.com/watch?v=D8TmA6-p35E
No emulators, cheats, hacks, or any of that crap was used in this video.