Really digging the concept (Pun intended)
The Ai is of course in need of some tweaking, but you've heard it already from the other commenters, so i'm going to highlight some of the other aspects that could use some work on.
Player one not having the ability to block a square seems odd to me, altough i can see that it could be done to prevent every game ending in a draw.
The text on the options is barely readable and the restart button took me about 5 games to find lmao (This one's probably on me though, bad eyesight)
I've had a bug where player one's red acorn does the effect of the yellow one (Idk why, it just happened once though)
And yeah, i think that's everything covered of which i found. Good luck! Really nice concept for a first game