Which game to play against aliens?

[ilya]

Ok, here's the deal. One day aliens show up in Earth orbit and after flying around for a bit they summon the Earth's leaders to a conference. It turns out that these aliens love to play games for high stakes. So they make us an offer we can't refuse:

We must send a representative to play against them in a game of our choosing. The game can be of any sort, and it can be either an existing game or one created specifically for this challenge.

We have a year to decide on the game. At that point, we must provide the aliens with a complete & accurate set of rules. The aliens will then have one year to practice the game.

After that second year passes, the human and alien representatives play a best-of-100 match. If the humans score 61 or more wins, the aliens will tell us their scientific secrets & give us their technology. They will also pledge never to attack us & to help us fight against future threats.

If we score between 40 and 60 wins, the aliens will simply leave.

If we score 39 or fewer wins, the aliens will immediately annihilate us.


What game should we choose?