Using free program Open Broadcast Software: https://obsproject.com

Twitch! https://www.twitch.tv


A few examples:

Battlefield 1: https://www.twitch.tv/directory/game/Battlefield%201

COD Infinite Warfare: https://www.twitch.tv/directory/game...nite%20Warfare

Halo 5: https://www.twitch.tv/directory/game...5:%20Guardians