Arkanoid Editor

The easiest way is just to use DATA statements as a poor man's editor, like:

; Key:
; 0 = space
; 1 = red block
; 2 = blue block
; 3 = unbreakable block
; etc.
.level1
DATA 0,0,0,0,0,0,0,0,0,0,0,0,0
DATA 0,1,1,1,1,1,1,1,1,1,1,1,0
DATA 0,2,2,2,2,2,2,2,2,2,2,2,0
DATA 0,3,3,3,3,0,0,0,3,3,3,3,0
DATA 0,0,0,0,0,0,0,0,0,0,0,0,0
 .
 .
 .

It may be better to use DATA strings if you have loads of different block types etc.

Not ideal but it's a start. ;)