So, where were we? Oh, yes. As the French, cutting off play at the end of 1907 (must check and see if this was a famous date in French history), as the Americans, playing until the cows come home. Let's see if we can find a happy medium from first principles...
It is a principle of economics that a subsidy creates more of a product or service, and in America the subsidy is that of time, which has become free, and thus suboptimal. In France, the issue is dealt with by strict rationing, again, suboptimal.
The first point to get straight is that a player's tournament score is the sum of his game scores. Each faction of a point is precious, and players with similar records will want to win the tiebreakers.
The concept behind the proposal may be considered simply. As the tournament winds down, there are players who have completed (and who would like closure), and there are players that have not. The longer a player has to wait around, the more irritated he will get. Perhaps this isn't a linear function of time, but certainly the trend is upward.) Tables that are eliminating players are doing their jobs. Tables that have concluded have done their jobs. Tables that indulge in Calhamer's fantasy of a perpetual pendulum of procrastination are not.
It works this way:
Each table starts with X points in a prize pool. Probably about 10, on gut feel. We'll assume a straight division of the prize pool among the active players at the end of play. There is also a survival pool. Points that go into the survival pool are immediately divided among the players then in play. Recap: Big bonus for making it to the end; dribbles along the way.
Let's assume N tables are playing in a tournament round of Diplomacy, and further assume that the tables are full.
Each year (two turns) after a player is eliminated, wins, or participates in a draw, 1/(7(N-1)) points in total are removed from the prize pools of the other tables in still play. Half of the amount extracted from a table's prize pool is placed in the survival pool. The other half is lost.
The consequences? Not much for quite some time. I'll illustrate how it works with a ten-table tournament. The first eliminee gets nothing for the round, which is what he deserves. At this point every other table is in a figurative hourglass with the sands running out. Starting with the next year, the elimination causes 1/63 of a point in total to be deducted from the other nine tables (or 1/567) from each table, of which half (1/1134) is split among each of the players at each other table. Virtually nothing -- except for the purpose of tie breaking. Each further elimination causes the same amount of carnage. Not much at first.
Even as the number of eliminees approaches half of the total players, there still isn't much real issue. 35 players gone of the above 10 tables, and let's assume seven tables are still in play...
35/63 points are removed from the prize pools at the remaining 7 tables, or an average 5/63 of a point per table per year (this will vary. Tables that have not eliminated players will lose points faster than other tables), and 1/126th of a point flows to the survivors to date (again, on average).
With two tables left, an average of just under 1/2 point will be deducted per year per table, and the final table will lose (exactly) a full point from its prize pool every year. If the table runs out of points, there's no point in playing. And there's considerable point in coming to terms before the sand runs out Perhaps the proposed starting value of 10 points is too much, but that's my gut feel for a reasonable amount.
Why this complicated mechanism?
1: It's reasonable not to penalize tables for taking a normal number of turns, and even reasonable not to penalize them much for taking a bit more than average.
2: The point of winning or drawing is a share of the prize pool.
3: The survival pool is designed to encourage losing players to fight to the end. Pride only goes so far in the face of certain doom. While the survival pool is a comparative pittance per year (at least until you're at the final table), it can add up for breaking ties. And you get the added satisfaction of taking your treacherous opponents to Hell with you.
4: The prize pool decrements are designed to be more psychological than actual in the early stages -- and positively nerve-racking at the end.
Why, you ask, are the deductions on a yearly basis, and not per turn? Simple. It's difficult to kill someone in a spring turn. If you understand Diplomacy you'll know why, and if you don't, the explanation is tedious.
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One other possibility occured to me today. Tournaments make a big deal about how to score points for games, and you wouldn't believe how much literature and variation there is on topic. (I think there's an earlier post about nearly optimal ideas get the most intense scrutiny.) C-Diplo is merely one of about 15 ways to score tournaments that I know about.
One idea that seems not to have been considered in the literature is: Let the players decide how to divvy up the points. My guess is that this could give nightmares to games in flux, as the weak sisters in a game bargain for more status than they might deserve, as the sand in the hourglass (and points in play for the game) start(s) running out...