[Lesane]

You could use sessions for that.

When they are going to the play action (tetris?action=play) then you can set a session name for example:

PHP Code:

session_start();
session_register("test"); 


Then by the code of reg (tetris?action=reg) you can check if the user has a session named test by the following code:

PHP Code:

if (session_is_registered("test")) {
echo "User has a session named test so he came from the play action";
} else {
echo "ooops, cheatterr";
}