I'd like to know how to render games like a.e. Imscared https://gamejolt.com/games/imscared-a-pixelated-nightmare/10058
Its a great game and I wanted some games with a similar art style so.....
You just render the game in a lower resolution and then upscale it without interpolation to achieve large pixels.
The one thing where you would need a shader for is reducing the number of colors. You can do that with a pixel shader which only outputs a reduced color palette. You can do that by simply discarding the last few bits of the R, G and B component.