Yes 3D tiles remember some retro style, some simplification of complex world.

The lines comes from non perfect textures, and what you see in Blender is just 3D tiles snapped with SHIFT - S without removing double vertex.
On top view, you don't see the seams after oushing the button : remove doubles laugh

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Making a big level on Blender this is LONG and TEDIOUS !
Only if i use some small rooms as Zelda from NES, i 'll continue Blender without custom editor.
For bigger worlds , you need some editor !

Just do It !!

http://independentcreator.over-blog.com/pages/3D_Models-7792999.html