My entry to the gfx compo at Gubbdata 2018. Came 3rd this year.
Based on this sketch by iLKke.
Standard C64 MCOL plus an additional sprite layer which gives 1 extra colour globally, resulting in 2 fixed colours + 3, instead of 1+3, per 4x8 pixels.
Other entries can be seen here. | 
Top Pixel Art - July 2018 (#6)
This is so cool and inspriing. It's hard to describe how unique it is. I'd love to see more of this world in action