Puzzle Problem

Hi, i am helping a friend with his game. Right now i am doing a puzzle that is sopused that the hero will enter a room, then in the room he will have to walk in every tile at least once to open the door, but if he steps a tile for second time the game will over.*Zelda games and other games have this puzzle and i love it*.
If you don't understand what i say you can see this picture of the map i did.
http://img525.imageshack.us/img525/7002/laberynth8ii.png
every time the hero steps a tile it is sopused to change color *from that yellow to the brown one* and if he steps a brown one it will be game over.
 The problem is that the only way  i know to do it is using 256 independent variables, and i am not feeling like going though each tile programing the event to use a diferent variable.
Basically i want to make a tile that you can only step it once then it change of chip and if you step it again it will kill you, and you need to step all this kind of tiles in the map to progress. Also i am using Rpg maker 2000.
So does someone know a way to do that with only a few variables or the only way is the one that i already thought?
Thanks in advanced.

Actually, you would only need 25 varibles.

Create a page where it's just the switch. Then create a 2nd page, where the varible is equal to one. Have the animation be of the yellow rock. Do the same thing, only this time, the rock is brown, and the varible must be 2 or higher. Then, repeat, one varible for each rock. Then, to change the rocks, have it on hero touch, and when he steps on it, add 1 to each varible that corresponds to the rocks you want to change. But yeah, that;s a simple as I can make it.

I will try that, thanks.

Actually, you would only need 25 varibles.

Create a page where it's just the switch. Then create a 2nd page, where the varible is equal to one. Have the animation be of the yellow rock. Do the same thing, only this time, the rock is brown, and the varible must be 2 or higher. Then, repeat, one varible for each rock. Then, to change the rocks, have it on hero touch, and when he steps on it, add 1 to each varible that corresponds to the rocks you want to change. But yeah, that;s a simple as I can make it.

I just noticed that, the rocks only have to stay there and are obstacles, i want to change the floor.

oh. Well, then yeah. You need about 100 varibles.

oh. Well, then yeah. You need about 100 varibles.

I was afraid of that, well then thanks for your help, i guess i will start now.