I wanted to make a chess map but I am not sure if it possible to stop players from making illegal or multiple moves in one turn. If anyone knows how I can do this if at all please help.

It IS possible but you would need an incredible amount of trigger to make it work somehow (probably not very convenient) and I'd say its not worth the trouble.

For checking valid moves you could use a mobile grid or
a coordinate system and arithmetics.

It's been done.

How would I even start doing that? LOL I am aware that it would take awhile but I want to learn how to do it.

Really? WOW never heard of it. Do you have it? or a link? I'd like to see it.

I kinda made this up right now but:

Step-1
Name your Units As Follows:
King, Queen, Rook, Bishop, Knight, Pawn, Selector (fast flying unit that can attack ground). From there you can name whatever the hell you want

Step-2
Make 64 3x3 locations and tile them so they align 8x8

Step-3
Have an area where the selector will be placed. Say this is "Unit Select".
Turn Start, Give Player 1 unit Selector at loc "Unit select"
Create units king, etc...
Player 1 kills [unit]
Remove all units
Spawn 1 [selected unit] at location "READY"
Spawn 2 [selected unit] at location "Unit Select" One belonging to P8, the other P7
Player kills P8, player selects the right, and so on.

Step-1
Player has selected [example: RooK]
Spawn Selecor at "Chess Board"
Create [Target (air unit)] at vaild..

ok, ill continue this later... im to lazy to work it out right now

LOL, I forgot to attach the map.

It'd be so much easier just to use mobile grids...

That too, but meh, its my way.

To Presige:

Sorry man, but moose posted the map. Im too lazy to do it if someone already has.