"Endgame" refers to the final stage or goal in any activity, plan, or competition. It represents the ultimate outcome or result that someone is working towards or trying to achieve. Full definition
There's an especially robust amount of endgame content as well, with huge new hunts, secret dungeons, secret weapons, and a fantastic car upgrade that can be found. (monstervine.com)
With each iteration being remarkably better than the last while also streamlining a few game mechanics to entice new players but still provides a challenging endgame for vets. (cultureofgaming.com)
Why would a casual player play a game they're not enjoying a couple hours a weeks in hopes to be able to participate in endgame in a year or two? (massivelyop.com)