Raptor doesn't pretend to be anything it's not. It's a vertical-scrolling shooter, you blow up enemies, earn cash, buy weapons and blow up more enemies. The game is short enough that by the time you get tired of its relatively basic mechanics, it's just about through, and you know you'll get an itch to do it all over again a couple of months later.
I love this game for its world building, its quirky anime-inspired characters, the mostly OK voice acting, and the music (however few and far between the tracks are). This game sets a mood that keeps me coming back to it every few years despite its limitations. Gameplay-wise, it's like a JRPG played with the mouse. Basically, the first half of this game deserves 5 stars, but after that the story-to-grind ratio becomes ridiculously skewed in the favour of trash mobs. The later levels are wrought with so many of them, and combat is so slow, even when your party is overpowered it takes forever. I recommend you buy it on sale, play the first ten hours with tutorials handy. Then, if you feel up to it, see how far you make it into the end game before you quit due to boredom.