This is a concept that was presented to me some time ago that stuck with me, and has proven to be a kick at the table.
Most groups play RPGs as consistent games from week-to-week, progressing through various levels a bit at a time. Problem is, things can get old in a game like that – the story can begin to drag or the characters get too powerful for common villains (ever played a Ranger in epic levels and get much use out of that Favored Enemy: Goblin?).
Playing by Seasons
One thing that kicked in my mind as a player of Fate Core was the idea that a major milestone is something akin to the finale of a television season. If it helps (as it does me) you can equate this idea to the comic book story arcs that become trade paperbacks. They’re part of the ongoing tale, but have a beginning and ending with a full arc between. That’s the way I enjoy my roleplaying now, and what the Perpetual Motion Engine is being developed to accommodate.
Implementing This Play Style
The idea is that the GM tells you what the situation (the problem the PC’s exist to resolve) is before character creation begins. This serves two purposes: to give everyone the same goal by the end of the story, and allow players to create relevant characters. The game can go off on tangents here and there (filler episodes) but resolving the situation should be the focus of play (getting the required objects/power to become powerful enough to resolve the situation).
Once the situation is finally resolved (whether that takes a single session or 10) the game ends. That’s it. Over. That doesn’t mean the characters can’t continue on in another season (a new situation), but when you do come back, create the characters all new.