It's good but short. I would keep playing it thinking there were multiple endings which there are not but the gameplay is fun. I ended up getting addicted to attempting to not die during levels. Free DLC is coming out for it but as of right now it has no release date.
Is it worth 15 dollars? It is a good game. I can tell the team that made this did put a lot of effort into it, gameplay, writing, art style. For me it was worth getting. As far as available Indie Games go, Katana Zero is clearly a step above the competition. I want to support the developers of these kinds of games that actually show talent. I would love to see what they come up with in the future. so pay the 15 dollars damn it.