That actually would be pretty easy, unfortunately, its a bit harder than that

Matrix:
[111111]
[222222]
[333333]
[444444]
[555555]
[666666]

Your map would look like:

1   1   1   1   1   1
  2   2   2   2   2   2
3   3   3   3   3   3
  4   4   4   4   4   4
5   5   5   5   5   5
  6   6   6   6   6   6

See what it does?  This was used to get speed from the xLib tilemapper, as each row could be mapped all at once.

(I never thought of using graphics to explain it, silly me )

Yeah, hmmmm.  I know Y-chat is just a cloned version of X-chat, but I also noticed it still was called X-chat in some places, and Y-chat in others

They must have forgotten to change some parts of the source they ripped from x-chat

It would actually be very fast, using only a single matrix access.  The only difficult part would be setting up the code to handle the offset variable.  The weirdest thing is that the cells relative to your cell are not constantly defined inside the matrix, they are dependent on your position.  (What i mean to say is that if you are at 1,1 inside the matrix, the cell below you graphically does not have any set offset inside the matrix )

Yeah, it works in a very unorthodox way to preserve speed.   But i think this would be a very good application for the engine. 

You should totally use my Isometric engine (^^,)

Yeah, same here.  The link seems broken

Its on the right?  Oh well, it doesn't matter anyway, I was just curious   Carry on!