In reply to La_Vie_En_Rose:
I found this list of those who went to the last world games in 2013:
http://www.ifsc-climbing.org/images/World_competitions/World_Games/130731_Q...
Essentially a mixture of winners and runners up from the previous year's World Championships, and a whole load of world and continental senior/youth champions. I'm not sure how the qualifying selection will vary this time around as there will be a total of 72 climbers there (24 each for lead, speed and bouldering, I'm presuming a 50/50 male/female split).
No real info on any of the official World Games/IFSC websites, however wikipedia has a list of participating countries and how many athletes they are each sending to the games (for all sports). There's no source given for this at the moment.
http://en.wikipedia.org/wiki/World_Games_2017#Participating_nations