Hans Eli Sebastian Fors, known by the pseudonym Forsen, is a Swedish streamer who is known for competing in Hearthstone. He usually streams Player Unknown's Battlegrounds and has previously streamed Hearthstone. wikipedia.org
Definition #2 for "forsen"
Forsen is the gamer handle of Twitch streamer Sebastian Fors. Online, his fans are well known for spreading Twitch memes, most notably popularizing Ugandan Knuckles.