Hi, I lost couple of times because I was building diagonal lines ! And later I realized that only orthogonal 4 in a row counts to win. Then I found it in the rules, however game description on itch.io page is not mentioning diagonals, I'd suggest to add them as playable, would be more options to play :)
Otherwise game is done well , idea is catching, implementation is simple and stylish enough. Good job !
Tried also online game in 2 tabs, cool , it works ! Is it on Photon , PUN Free tier ?
Thanks !