A game tournament lasting an afternoon, mostly abstracts. Something over three hours, playing 18 games, a new one every ten minutes. Players play an average of at least three games. Just the game schedule is mapped out, not the players. Players can be tossed into playing a game if the player is available and wants to play/is good at the game. Mystery games are possible, and have the benefit that players don't have to learn beforehand.

Get a dozen (ten?) people, kind of friends, and attempt to divide them into two equally-skilled teams. Do so in advance, so they can get coverage in terms of players learning the games.

This seems more doable than fanciful.

Here's the fun part. What games would they play?
 
 
 
 

The vast majority of games would be two-player abstract strategy. But you might find yourself playing a Finnish card game or dominoes or something dicey, for variety. Certainly you can find a dexterity game, such as darts, fussball or a don't-topple game.