Help with game phase identification I'm working on a chess AI for a school project and I am looking into ways to identify the current phase of a board, meaning the opening, middlegame, and  endgame. I have seen an article explaining Tapered Evaluation, however I don't really understand what the point of this is. I want to be able to change my overall board evaluation heuristic depending on what state the game is in. This way, in the middlegame, I can prioritize king protection and development and other strategies.
I think you don't need this. You shift from opening to middle game when your opening book for this line runs out.
The middle-end phase is less relevant in AI, and your algorithm will handle those the same. You could define a line, e.g. when your search depth could be increased over some threshold, because the board has only a handful of pieces left, but I don't think it's an important change.