Free Guard Zone
It's just a few hours until my first League game, and the official rules just arrived via E-Mail.
Most of them are mechanics: match time, when you're supposed to show up, etc.
The interesting rule is the Free Guard Zone rule. It states:
"No rock lying in the free guard zone can be removed from play by the opposition until the first four rocks of the end have come to rest. The free guard zone shall be the area between the hog line and the tee line, excluding the house."
The rule was first suggested in the early 1990's, and adopted quickly. It makes Curling more fun.
Before this rule, it was possible to a very conservative strategy where the first rock in an end was thrown, and the opposing rink took it out. The two rinks simply swapped stones until the last stone was thrown, ending with a 1-ender. Kinda boring.
Because the free guards can't be removed early, more rocks are in play, and that encourages a more aggressive strategy.
... and a more interesting game.
Seems like every match uses some variant of the Free Guard Zone rule.