Pretty cool Adrien. I just gave it a short try and soon figured out the basic concept. I think what's missing the most is user feedback. E.g. it's hard to see whether you actually hit an enemy. Some take two hits and you might have hit it but don't even know. That kind of thing.
I think it might also be buggy, shooting through walls may be possible for you or the enemy, but I'm not 100% on that. On the other hand that could also be a level design element, walls you can shoot through in one direction. https://en.wikipedia.org/wiki/Embrasure