Day 15 - Describe a tricky RPG experience that you enjoyed.
Another one that's no so easy...
If there is one of these that I've enjoyed the last few years, it had to be running a session of the Coriolis - The Third Horizon RPG. Specifically running "The Dying Ship" scenario for the game that has some interesting challenges to it. And no, I'm not going to get specific here, because I don't want to spoil the adventure for anyone running or playing it!
In the past, I'd say the trickiest experience I had was running a session of the Universe SF RPG from the folks at the now defunct SPI gaming company. The player characters had a ship called the Lucky Lucy and were fleeing an enemy vessel through an asteroid belt. It was tricky for me because the players insisted I do all the math for the vectors and the like for them, and I was also doing the math for the enemy vessel as well!
I loved every minute of both experiences, but oy vey! what a headache I had after that week's session was done! :)