Fastest way for tiled & Pixelated background

I would like to do something like this: The Cave : bathing, throwing stones, and catching a fish with bare hands! - YouTube

I tried doing it by creating a background GUI texture and directly modifying it’s pixels but that turned out to be very slow with one update per second which is just not enough. Is there any other way to do something like that? Could a sprite manager be fast enough to have 30 FPS with hundreds of pixels on screen (especially important for iOS devices)? Does anyone have any other idea on how could this be done? It is also important that the pixels can be tinted with colors so I don’t have to have images for them in each color I want to support.

Have a look at 2D tool kit and other sprite managers. If all your sprites are on one sprite sheet they will all draw in one draw call so it is fast on iOS.