***The doors actually manage to fit well in the background.
***Sprites and Scenery elements (objects, doors, platforms...) : they use only 3 colours and the 4th ink (ink number0) is used to get the transparency mask.
[[File:Heroquest possible colour variation.png]]
A more clever use of the transparency/mask ink with the Floor/Wall tiles could enable to display this '''background grey''' in those floor/wall tiles but it wasn't done... which is a serious graphical limitation alongside a poor colours choice, which leads to the sprites and scenery being quite blurred into a blue messy hell as the background can't differenciate differentiate properly through the use of an additional different colour.
It is also to notice that some basic floor tiles use only 2 inks+transparency (Blue and dark blue) the "light cyan" seen in the jointed floor-tiles being then obtained by the pixels-crossing from 2 different Floor-tiles.