Pretty cool actually! Menus are very slick and remind me of something I might have played more around the era of DOS 6.22 from a cover disk or BBS.
First impressions were pretty good. Bomb was satisfying, music and sounds were spot on for the feel you're going for. Boss music was nice and menacing.
Gameplay criticisms I would give - please bear in mind this is all personal taste and your game is still good regardless:-
* Stage was very long -- your game (at least on hard difficulty) should induce restart syndrome and leave me wanting one more go
* I actually became annoyed with the sideways shooting powerup and wished there was a way to either cycle the weapons I picked up, or combine them ala Xenon 2 / Tyrian - However the sideways shot utterly destroyed the level boss by spending about 90% of the fight hovering under P1's score since he doesn't go to the screen edge - so definately make him attack more screen estate horizontally and try to funnel the player in to his bullet streams.
* I think if you were to combine (stack) the powerups or allow switching between them, this would really enhance your game as the player would then have a goal of collecting all 4 shot types as the level progresses to deal with the increase in enemy count/difficulty as the game goes on. Part of the fun of shmups (for me) is decisions that must be made regarding when to make use of or collect your powerups. For example in my game - do I shoot the bullet cancel enemy first, or do I turn his bullets in to coins by activating hyper and then use him to clear up his second wave of attacks? That'll give me 50% meter back and make it more likely that I'll rebuild my meter for the next segment.... but if I sacrifice a little score here.. I could generate a larger chain from hyper shots.. etc etc.
In your game, I would say definately build upon your powerup system and incorporate some more risk/reward decision making moments in there.
Good job so far! Keep it coming
it's really helped.