Really fun!

Biggest score was 180 and the teleportation does come into good use, when dodging the projectiles.

Just next time have your tutorial show up during the beginning of the game. I've done playtest sessions for game jams and school projects, and having a "How to Play" on your menu, and not include it after the player starts your game, will cause some red flags. So it's best to briefly state the objective and show what the controls are, once the player launches your game.

I'm kind of sad that there's no music here :(

Overall, I enjoyed it. Keep it up!

P.S. What is my character and who is he/she fighting? 

Cool game, I like the feel of the game how sombre and maybe kinda scary it is. The sound does fit nicely with the aesthetic. but the sound effects (mainly the gun) can get boring over time.

cool idea but I think some extra particle systems and some nice lighting would have made really good. 

Good. game, only thing missing is non invisible walls, and other sounds.