A few thoughts:
- You know how to make white circles, so it should be fairly straight forward to make black/red ones.
- The users only have to pick the column, so I would have 7 buttons on the top so whoever's turn it is just clicks the button.
- I would keep the values in a matrix of -1s 0s and 1s for red unused and black.
- Whatever column is selected the zero in the biggest row is turned to the respective color
- You can use conv2 or bwhitmiss (I like conv2) with the ' valid' option and four different kernels (one for each way to win: horizontal 4 vertical 4, diagonal and antidiagonal) call conv2 four times per turn to see if that player won.
- Enjoy writing the game and good luck. Logic games are fun to write but the progress slows greatly when you have a working version and can start playing!
