Thank you! Othello is one of my favorite board games. Perhaps you have already noticed that I am using BASIC code to develop this game, but it compiles into GBVM instructions similar to GBS. So I believe you could achieve it as well with GBS, GBVM, or even GBDK C or ASM. The code for this game can be seen when you choose the “Reversi” starter kit while creating a project in GB BASIC, feel free to check out the code if you think it might be helpful. There is a web-based development environment available here: https://tonywang.itch.io/gbbasic
And be sure to tell me when your Othello is finished, I’ll definitely give it a try!