Thank you, I'm glad you like it.
The game uses some simple raycasting to create its pseudo-3d look. I used this link and this video as references while creating it.
In order to try and keep the game as pixel-perfect as possible I used shaders to draw the 'textures' on the walls (including the stairs and chests), and those shaders will draw them differently depending on if they are viewed from the front or the side. That's why you can suddenly see the stairs or chests snap from a front-view to a side-view if you rotate the camera while standing next to them.
The game will first draw everything onto a canvas in black and white, and then when drawing the canvas to the screen I used another shader that will check the average color of each pixel and change it to either the light or dark color of the current palette. That way I can be extra sure that there are only ever two colors drawn to the screen at once.