Recently I got to try Pandemic. In this game four diseases threaten to wipe out mankind. The players must work together to keep the plagues from spreading while racing to find a cure before time runs out. Each player can be one of five roles (7 roles in the new version) which grant them special abilities. Like the Researcher who can give any card in any location, instead of just the card corresponding to that location. This is important because a set of 5 (or 4 for the Scientist) cards of the same color are needed to cure a disease. It is a very good game and I recommend that you give it a try when you have the chance.
When I was playing with some friends, they were playing that you could only give cards on the giving player's turn and were finding the game quite challenging. Most of that first game with them was spent figuring out how the receiver could end up in the correct city to be given the card they needed. This made the game more an exercise in creating board moving than actually about stopping pandemics and it wasted a lot of turns, which are really the limiting factor in Pandemic.
After some rules discussion, we played the next game by relaxing that giving cards could be done on either the giver's or receiver's turns. The difference in difficulty was astounding. We won easy without a sweat, whereas before it was more like a coin flip. The other big difference to me was the type of discussions we were having. Instead of trying to go through weird gyrations to pass cards, we talked more about stopping diseases. Now we debated the trade-off of heading off the spread of a plague or getting a cure for another sooner. The focus had returned to what the designers had in mind, instead of trying to go through the gyrations of a small rule.
This was a very nice example of how a very simple rule change could have a dramatic impact on how the game is played and really the quality of the game. The lesson I took away from this is when most of the discussions in a game are about how to work within one rule, unless that rule is central to the concept of the game, there is probably something wrong. And then letting the players do what they want to, give cards on any turn in this case, can make a more enjoyable experience as then the players' focus is not distracted by obtuse rules.