A fond thank you to Luiz Melo...

I used his following sprites:

Pollux sprite: https://luizmelo.itch.io/heavy-armor-2

Castor sprite: https://luizmelo.itch.io/heavy-armor

Soul warrior sprite: https://luizmelo.itch.io/ghost-warrior-3

Tutorial troll sprite: https://luizmelo.itch.io/fantasy-troll

Stranger sprite: https://luizmelo.itch.io/dark-knight

Ranged zombie sprite: https://luizmelo.itch.io/fantasy-zombie

And another big thanks to Chiey...

His Demon slime animated sprite can be found on:

Cave demon sprite: https://chierit.itch.io/boss-demon-slime

...and furthermore to all of the following people for sharing their hardwork for free, so people like me can make beautiful games!

Cave and Forest Tileset made by Szadi art, found on: 

Forest tileset: https://szadiart.itch.io/paltformer-fantasy-complete

Cave tileset: https://szadiart.itch.io/pixel-fantasy-caves

Skeleton enemies: https://szadiart.itch.io/hero-and-opponents-animation

Main character spritesheet made by Kronovi-, found on:

Rogue Knight: https://darkpixel-kronovi.itch.io/rogue-knight (I have added and changed several animations)

Alagard font, used throughout the project,  by Pix3M, found on:

Alagard font: https://opengameart.org/content/pixel-fonts-by-pix3m

Dagger throw effect made by NYKNCK, found on:

One of the effects used on the dagger: https://nyknck.itch.io/fx071

Skeleton demon boss made by Ansimuz, found on:

Originally, it had only the idle and "soulbreath" animations: https://ansimuz.itch.io/gothicvania-patreon-collection

Main menu background made by vnitti, found on:

I edited the sprites to make it more suitable to my game and added some other stuff on top! But the original can be found here: https://vnitti.itch.io/grassy-mountains-parallax-background

If I forgot to mention an asset that is used in this project, and you'd like to see credits added, please reach me at gabrielconcencio@hotmail.com and I'll rectify it asap! Thank you for understanding! :)