'This or That' is a strange variant of Vertical TicTacToe, where the players limit the opponent's choices.
 
A player has won when there are THREE checkers of his colour in a row, either horizontally or vertically or diagonally. The two players Red and Black move in turn. In principle the moves are made like in Vertical_TicTacToe. However, you are not free in your choice. Instead, the opponent forbids all your moves except for two. These two remaining candidates are marked by crosses in your colour.
 
You click that cross you want to realize; and you have to click the other cross twice to make it disappear. After this you place the two candidates for your opponent. Red starts the game by placing two crosses for Black.
 
A complete turn consists of ten single actions:
(1) Cross 1    (2) Cross 2    (3) Black Checker    (4 & 5) Delete remaining Cross    (6) Cross 1    (7) Cross 2    (8) Red Checker    (9 & 10) Delete remaining Cross.
 
Therefore it is recommended to play 'This or That' on smaller boards and not on the typical 7x6-grid of Connect4.
 
The many single actions in a turn also mean that the Zillions engine has to search to something like depth 40 to detect a 'win in 5'. The picture below shows a situation where player Black has just placed the two candidates for his opponent. At search depth 42 Zillions has found that this is a 'Win in 5' for Black.
 
 
Strong strategies are still unknown. Players are welcome to let the author know about their good strategies. Contact: althofer@minet.uni-jena.de