Can you please help me find the name of this old dos/windows game from the late 80s/early 90s?

I've haven't seen it for 20 years. Here's what I remember. Black screen. White grid. Take turns placing balls into the boxes in the grid. It's a strategy/board game. Winner is one who dominates the board. I used to play it in school on a windows 3.1 or windows 95 machine. I remember that you place the dot and it would change the colour of those around it until someone has dominated the board and won. It was very basic. Thanks in advance!