I was invited to a Ticket to Ride game by someone from the boardgames subreddit.
I don't think I've ever played to prevent someone from accomplishing their goals before, but it was very satisfying.
I'm green and he is red.
He started out taking Los Angeles to Phoenix. Then Phoenix to Denver. Then Denver to Kansas City. I started to get nervous with all of my cities being in the east. (I also had Miami and Kansas City.) I hadn't even laid down any trains yet, but I had tons of cards.
I played Kansas City to Saint Louis to make sure I wouldn't lose that much needed section. Oddly, he then put a train down between Nashville and Atlanta. This let me know that he needed in there.
So I did what any nice guy would do -- I took Kansas City to Oklahoma City. Then I took Saint Louis to Chicago. I proceeded to make sure that I cut him off of almost every single path into the east while still building my routes.
He has since tried going from the east and then connecting to his route in the middle. But I'm pretty sure it's not possible for him to get enough white trains before I do. In the meantime, I have enough trains and cards to finish my routes anyway.
I have never played this cruelly before, but it has just been immensely satisfying.
I'm not sure if he's going to continue the game. We were playing at a good clip, and then he just stopped here.