I know it was not well explained. I'm sorry.
I will exemplify:
I have a Tileset made in Photshop with 8 tiles.
Tileset:
0,1,2,3,4,5,6,7,8
(0=floor, 1=door,2=tree,3=house,4=house,5=house,6=town hall,7=brigde,8=wall)
And I want to build a city like this:
8,8,1,1,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8
8,0,0,0,8,0,0,0,0,8,0,4,0,0,0,0,0,0,0,0,0,8,0,0,0,8,0,0,0,0,0,0,0,0,0,0,0,5,0,8
8,0,5,0,8,0,0,0,0,8,0,0,0,8,8,8,0,8,8,0,0,8,0,2,0,8,0,6,6,0,0,0,0,0,8,8,8,0,2,8
8,0,0,0,8,8,0,0,8,8,0,0,0,0,0,0,0,0,8,0,0,8,0,0,0,8,0,6,6,0,0,0,0,0,0,0,8,0,0,8
8,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,8,7,7,8,0,0,0,8,0,0,0,0,0,0,0,0,0,0,8,0,0,8
8,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,8,7,7,8,0,0,0,8,8,8,8,8,8,8,0,0,0,0,8,0,0,8
8,0,2,0,0,0,0,0,0,8,0,0,0,8,0,0,0,0,0,7,7,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,8
8,0,0,0,0,0,0,0,0,8,0,0,0,8,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,3,0,0,0,0,0,0,0,5,8
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,1,1,8,8,8
The characters would walk on 0 and 7, but would collide on 1,2,3,4,5,6 and 8