Here are some of the more advanced play rules and variations you'll encounter in the game. For basic rules and play strategy, see this Final Fantasy VIII Triple Triad Guide.
Same: When the Same rule is in play, if a card is placed and two of it's sides are equal to two adjacent cards then Same occurs. Note: one of the other cards involved can also be your own.
Plus: With the Plus rule in play, the value on the sides of your cards is added to the value on the sides of your opponents cards that it is adjacent to. If the sum of the sides adds up to the same number, then your opponents cards are flipped. For example, if you place down a card with a 1 on the left and a 6 on the right, and the 1 is adjacent to a 9 and the 6 to a 4, then both of your opponents cards will be flipped, instead of just the one with a 4 (1+9=10, 6+4=10).
Combo: With the Combo rule, cards that are flipped with Same/Plus/Samewall/Pluswall can also flip opponents cards adjacent to them if the side has a greater value. This is a complex and dangerous rule that requires extensive forethought in gameplay.
Same Wall: With Same Wall, the wall (edge) of the board is given the value of A. This means that it can be used with the Same rule in a more clever way. Basically, you can activate Same with only two cards down on the board by placing a card with A adjacent to a wall, with a number side matching your opponent's card.
Plus Wall: With Plus Wall, the wall (edge) of the board is given the value of 10. Much like with Same Wall, you can use this edge to your advantage when trying to make a Plus occur, as this edge counts as if it were an opposing card edge.
Elemental: With the Elemental rule in effect, element icons are randomly placed on the game board. If you match up the element in the space with the element on the card placed, each of the card's edge values will be increased by 1. However, if you place a card in an elemental space that does not match, each of the card's edge values will be decreased by 1.