I have played this variant numerous times with new players over the last 10 years, and it not only has resulted in more wins, but the losses have been much more entertaining!
First, you will need to arrange a "Sanction" - a punishment for the most selfish player in the event of a loss. You may want to be creative with this, but if it is too elaborate or disgusting, you might have players welch. I highly recommend using Harry Potter jelly bellys, as they are safe, small, but hilariously disgusting. The loser will have to chew (the chewing is very important, so that they don't just swallow the beans without tasting them.)
Before the game starts, you will need to explain the variant, and have everyone agree - on their own honor, in the spirit of good gaming - to accept the punishment meted out by the UN Sanctions should the group lose.
Now play the game.
If the group loses the game according to the conditions in the rulebook, all players must reveal the sets of cards they hoarded for points. The player who hoarded the most points is the pariah, and is singled out for "UN Sanctions" - that person is subject to the punishment agreed to.
I've found this variant works tremendously well for a number of reasons:
Simplicity - Very simple to explain.
Theme - When a nation attempts to hold the world hostage, sanctions often follow.
Game Tension - Hoarding is always fun in this game, but now it feels a bit risky, dangerous even.
Social Dynamic - When some players start hoarding more seriously, accusations will start flying about selfishness: visible points versus hidden.
End-game Satisfaction - The group gets a win with a winner, or gets to hoot and holler as the pariah is "Sanctioned".
There's no greater satisfaction than watching sweet, quiet Vanessa eat soap and rotten egg jelly bellys after hoarding 21 points in a loss...
They explained everything in detail and at great length. After they finished I sat, despondent, contemplating a bleak and empty future. "I’m glad you’re depressed" said one. "It means you’ve understood the situation.”
Hilarious - I like your style.
We need to introduce something similar to punish hoarders.