MIssing a double is a common mistake. The consequences are often not fully realized. Every chance you give your opponent a free roll, you risk giving away your advantage if they get lucky and happen to roll that magic number that gets them out of their predicament. Here is a fine example of such a scenario. My opponent was down to the last checker that I got lucky and hit. I closed out my board and was bearing off aggressively like I'm supposed to when we reach this position below. Underestimating my winning chances, I failed to double. It was a double pass I should have cashed out right there. Next turn the bot rolled 44, I got the taunting laugh of the bot lucky roll and that was it. Game over . Lost a chance to win the sweetest BG victory. That of winning with the last checker of opp hit. It is rare but does happen if you know how to play it. attached is the gnubg sgf file to replay how it played out.