It would be better to type the letters in a notepad file.Then have the blender game engine read them.
Then you could copy and paste the letters from any information you copied from the internet.
An array is the best way to store the info, but writing it out like this is a good way to edit levels quickly.
To avoid the empty floor problem:
You need to define a base tile; an empty square. Then go through and get any letter that isn’t either an empty square or a wall which will be an object or prop.
Put those things in a separate list with their co-ordinates.
Add the walls and floors (using the base tile where a prop is present), then go back and add all the other props such as player, enemy, keys and such at the right locations.