I think this is a bad scoring system.
First of all, all games on this site are zero-sum, and I think that they should be. I have a different look at solos. I see a solo more as a failure of the survivors than as an achievement of the winner, and it is a fact that the worse the players are on average, the more likely it is that someone will solo. Giving a higher total payoff for games in which someone solos does not make much sense to me.
The suggestion of nopunin10did in the post above me makes more sense to me since its zero-sum, but it still would be very weird to have. It would incentive players to stop a solo EVEN if they KNEW that would cause their elimination. This is just as strange as PPSC scoring, where players are incentiviced to take more supply centers, even if they know that will cause someone else to solo. Also, a side-effect of giving all players, even losing ones, an extra reason to help prevent a solo from occurring, might decrease, instead of increase, the number of solos that you would see.
If you really want to encourage solo attempts, then one should have a scoring system that, in case of a draw, gives a higher payoff to players that are closer to achieving a solo than to other players.
Consider two scenario's where some player (let's call him Bob) plays a classic game.
- Scenario A: Bob plays for the draw from the beginning onward. He allies with 3 other nations and eliminated the other 3 nations with his allies. After that, all players are roughly equal in size, and everyone draws.
- Scenario B: Bob attempts a solo. He comes very close; in fact, he reaches 17 supply centers. But he gets stalemated by the 4 surviving players on the other side of the stalemate line (none of which is very big in size) and has to accept a draw.
Under the scoring system we currently use at vDiplomacy, Bob would gain more points in scenario A than in scenario B. A better scoring system would give Bob a higher payoff in scenario B, as that scoring system would encourage solo attempts. There does exist precisely such a scoring system, and it's called Sum-Of-Squares Scoring. I am not in particular favoring that scoring system, as it has its own problems, but I think this is the right way to think about scoring systems and how to improve them.