I played Megaton Rainfall a while ago, when the game was exposed by Nerdcubed (check out their channel), and the game left an impression on me.
And a few years later, I've come back, and I'm ready to review.

This game captures something that I wasn't expecting from a Superhero game: existential horror. The game directly tells you that there is nothing in the universe except for Earth, and then goes and gives you the tools to go see for yourself. Flying though a solar system, a galaxy and even between galaxies, there's this pit of terror that...well there's nothing. It's all meaningless, except for Earth. And the only thing stopping Earth from being destroyed...is you. It's a perfect premise for a game about saving the world, and not worrying about the fact planets are procedural.

But what about the moment to moment gameplay?
Well, I enjoy it! This game is about making you feel so powerful that you can be reckless, and you'll need to hit shots precisely or you'll be killing more civilians than the intruders with fantastic feeling destruction. That being said, combat can feel clunky and like you're sitting and waiting, rather than fighting. It would be nice to see some more dynamic combat than "hit red/yellow".

And then the intruders run, so you chase after them, ascending among the atmosphere, and the music *hits*.

I'm someone that is very emotionally feeling when it comes to music, and the music in this game elevates it. There beautiful sections between combat, or in certain missions, or at the end of missions, and they just hit different in this game.
Flying over the Earth, mentally preparing for the next fight, it's something I've not really experienced in many other games.

It does everything it can to solidify this idea that you are the only hope for humanity, so get ready.

The story itself, like others have said, is weird, and coming back I still don't feel like I have a full grasp on aspects. I haven't found extras hidden among the galaxy, so perhaps there is some clarification there. Needless to say, this is a story that has some interpretation about what it means, which also feels very suited to this game's ideas of existentialism.

Overall, this experience is 100% worth your time, even if that time is very short (the game is quite small just going through the main campaign). Perhaps based on that, you could wait for a deal, but I think this game is still worth the asking price.