[gnramires]

Have you thought of going Shadertoy style and doing everything procedurally? Or every block procedurally? That way you can cut RAM as much as you wish. For example, if you have a procedural formula to determine if a block is populated, you don't need to store it in RAM, just use this formula in the renderer directly (in Shadertoys this usually would repeat per-pixel).

[nickmqb]

It did cross my mind. However, a problem with that approach is that evaluating such a formula is too costly/inaccurate on a small FPGA like this, which just has 8 DSPs (that can only do 16x16 bit multiplication), and some of these are already in use in other parts of the design.