Deep Blue, TurboGrafx 16.
Deep Blue is another shooter released exclusively on the TurboGrafx-16. It was released by Pack-In-Video/NEC in 1990 (1989 in Japan). This style of game was even more popular in Japan than North America so it isn’t surprising to see a bunch of them on the TG-16. Uniquely, Deep Blue has a nautical theme in which the player controls an Angel Fish.
Given the rarity of the system and the relative obscurity of the game it won’t come cheap (though worst case you shouldn’t have to pay more than what it cost new) but for shooter fans it is another decent title to have. Again, I am not aware of any ports or re-releases so a TurboGrafx-16 or emulator is the only way to play it.