Most programming languages allow for multi-dimensional arrays like MAP(16,16,256). This would stand for 16x by 16y by 256z (depth), which is incidentally the size of one Minecraft "chunk." It's made up of many such chunks, procedurally generated off into the distance.
Petit Computer only allows you to make 2 dimensional arrays. The largest array you can make, the absolute largest, is 512x512. After that, you can't DIM any other arrays at all, meaning no data for characters, monsters, inventory, etc.
A 512x512 array, if you could treat it like a 3 dimensional one, would contain the same number of elements as 4 Minecraft chunks. That's not much at all, a little 32x32 area of blocks to work with (that goes very deep). And like I said it leaves you with no space left to hold any other arrays at all.
Also the only way you can save data to be loaded later is in MEM files, which are nothing but strings of 256 characters. In order to save all the contents of a 512x512 array, you would need 1024 individual MEM files, which would be extremely annoying to manage if it's even possible. So no saving.
Also Petit Computer is super not-optimized for rendering anything in 3D at all. It might take 2 to 5 minutes to render a single screenshot of Minecraft, again, if that's even possible.