I scoff at all the things on this list. I play bullet hell baby.
Mushihimesama Futari
Dodonpachi SaiDaioujou
Crimzon Clover
EspRaDe
Espgaluda 2
Muchi Muchi Pork
Pink Sweets
For the record in these games you have to no death run, hardest difficulty sometimes new game plus in order to reach the TRUE ending of the game which ALWAYS has a special boss.
The most famous is Larsa from Mushihimesama Futari. Lately though SaidaiOujou and Crimzon Clover have been gaining a LOT of praise for their difficulty.
^until recently NO ONE had actually reached Inbachi and beaten them in Saidaioujou. fast forward toward the end to see why. So god damned fast...