The One-Percenters

Pandemic: Fall Of Rome cooperative boardgame.  You're in charge of defending Rome from the besieging hordes, generally trying to make friends (OK, probably slaves) of them so they stop attacking - though most of them seem to have 'not got the memo'.

There are many and various ways to lose this game.  

On the very last possible turn we were guaranteed to win unless I rolled something that would only happen on a 1-in-6 chance and if I then drew the wrong card which was a 1-in-25 chance - amounting to a less than 1% chance of losing the game

We lost.