[soumyaskartha]

Connect 4 is one of those games that looks simple until you realize it was solved in 1988 and the optimal strategy still takes serious compute to run in real time.

[tromp]

Not that serious, since you can solve the 7x6 game from scratch on a typical 2013 single core in a few minutes (and in 67s on an Apple M2):

    $ time ./SearchGame < input.root 
    Fhourstones 3.2 (C)
    Boardsize = 7x6
    Using 8306069 transposition table entries of size 8.
    
    Solving 0-ply position after  . . .
    44+26
    45+28
    42+27
    47+26
    4-29
    +29
    score = 5 (+)  work = 29
    1479113766 pos / 139494 msec = 10603.4 Kpos/sec
    - 0.249  < 0.125  = 0.027  > 0.191  + 0.408
    
    real    2m24.904s