
Note that "Manic" in shmup term (for me) isn't only related to "Hardest shmup" or 'bullet hell' or 'crazy bullet dodging' or whatever, also it can be like toughest obstacles in shmup, unfair rank system, cheapest moment, etc depending what your definitons about the term "Manic".
Here's some Manic-est shooter i've ever played ( so far ) :
AP Batrider
Gradius III arcade
Gunbird 2
Sexy Parodius
R-Type 2 arcade Japan ver
Mushihimesama Ultra mode
Ikaruga
DDP DOJ white label