I loved playing Connect 4 as a child - and I still do today! I never thought I would build one as a computer game. The hardest part was figuring out and programming the diagonal victories. You can either pick dark-red or pink to play. Every move is accompanied by a sound. When one color wins, the whole board expands and the winning color fills the screen. This animation I did with jQuery. Additionally, there is a winning-message blinking - I programmed this in CSS with animations and keyframes. The 'Play again' button restarts a new game - you should give it a shot!
Go to 'Connect 4' project