We set up both boards for the Rise of the Elder Things ancient one in Eldritch Horror. The game took almost 5 hours, with a few breaks, and used up a phenomenal amount of brain power.
We won. We had to solve four mysteries before time ran out and the doom track went down to 7, which was only two or three bad turns way from the ancient one awakening.
The game never felt like it was getting away from us, but it did seem very hard to make progress. It was about two hours before we managed to get even the first mystery solved.