Around 6 hours 15 minutes to beat (Win a match). The AI is pretty brutal and will take over the board chaining multiple turns in a row. Many times I would be doing well only to end up with 1 piece left by the end. I had a tie game today too for the first time so I knew I was getting closer.
I have only beaten a few Othello video games so not alot of experience with the tactics involved. I looked up some strategies quickly and that helped but it still took a while to break through. Some things I tried to do was intercept moves by disrupting them, take over corners and edges when possible (these cant be sandwhiched by the AI), and start off my keeping my score very low , while trying to set up moves for later. Also avoiding obvious traps where I would gain alot of pieces but then have them taken back immediately.