While I suspect the “melancholic exploration adventure/arcade-style twitch shooter” isn’t going to be the next big thing anytime soon, if you want a game that fits that bill exactly, you’ll really want to snap up developer YCJY’s The Aquatic Adventure of The Last Human on PS4 (or Steam) at some point. It’s a great and intentionally gloomy game with solid controls and some pretty (and pretty colorful to pretty dark) underwater environments where exploration is somewhat languid until you accidentally or with intent pilot your little gray submarine into brutal boss fights that give you a run for your money.
The game is a somewhat thoughtful and dour (but overall excellent) look at the last survivor of the human race crashing back on earth after an extended space flight only to find the planet covered in water and ice with dead cities full of clues under the sea and assorted sea life. As you explore the non-linear map you’ll discover most of the creatures are harmless, but as noted, you’ll be in for a more than a few jolts when you get into those tough boss battles. It’s more or less a depressing version of Darius done in the versatile Gamemaker engine with some solid pixel art that recalls a nice hybrid of 8 and 16-bit art styles with some modern lighting effects.