The Othello..... I downloaded it from the app store on my phone, but I believe there's a web-based version (based on a YouTube video I watched.) I set it to level 30 and it spanked this game's A.I. My friend beat this A.I. on the hardest difficulty on her first try using it.
What you do is set "The Othello" A.I. to level 30, and set your opponent's color as white. Then, on Steam Othello, set your opponent's color as Black. What you're doing is setting the A.I. against each other. Mimic the moves played by Steam Othello on "The Othello" and when "The Othello" responds, play that move on Steam.
The Steam A.I. won't stand a chance against the extremely aggressive level 30 A.I. of The Othello.
If you think this guide is cheating or cheap, then that's ok. If you're good enough to get this without using this method, then you should be good enough to not need a guide anyway. Even if you're playing this game for fun, as I am, it's still nice to have the achievement.