I have put the stuff that I learned with my game into an example.

It simply creates a 32x32 or 64x64 map with 16x16 sprites programmatically, so that you need no tool support. I guess this style was already retro in the 90's... 😃

Furthermore it shows how to create and update sprites in memory.
To take it to the extreme, it converts the famous Boulder Dash sprite from its original C64 ASM on the fly!
Hope you find it useful.