Estimating FORG1VEN's IQ
FORG1VEN is an infamous LoL pro who was known for his skill and crazy personality. By vrazy personality, I mean that he has a tendency to get angry at teammates if they don't play up to his standards, he taunts former teammates and accuses them of being shokers. Later in his career he returned to play in 2020 for S04, the team lost 7 games in a row, prompting him to lash out on stream and criticize the team's roster after he "left".
Despite this, teammates who found him difficult to work or outright disliked him, like Jankos or Youngbuck, thought he was extremely good. nRated even considered him the best player he had played with, even after playing with some of Europe's best players ever. UZI, arguably the best AD carry player ever, had this to say about practicing against him:
"So with H2k, we've actually played a lot of scrims against them," he said. "At first, our bot lane always had an advantage, but as our scrims went on and the more games we played against H2k, I felt that Forg1ven is a player that has a very strong will and he's a really fast learner. He started learning how to play against us even when we picked [bottom lane] champions that are much stronger against their team comp. In the end, it's starting to get much harder for us to get any advantage in the bot lane against them.
"I think Forg1ven is a superstrong player. He has a lot of great mechanical skills, and he is superfast learner," Uzi said.
Finally, he wanted to address Forg1ven directly.
"If we do meet, I want to meet you at the final, Forg1ven," said Uzi. "I do recognize you as a great opponent. [Also] you're a really friendly person. You added me in-game even though I don't speak English, and you'll always say hi to me. But I do want to meet you in the finals."
It is worth noting that both nRated and UZI highlighted his intelligence when they were talking about his skill in the game and the reasons for him achieving it. He also has a track record of being extremely good at other games which are very different to League of Legends. For example, in CSGO he achieved global elite (top 1-2%), he was top 400 in the Overwatch beta, and he achieved rank 2 in Heroes of the Storm [source]. I want to clarify that getting x rank on the competitive ladder doesn't necessarily mean you are the x best player of that game at that time - many people get these ranks and they shift around frequently. However, I would be comfortable claiming that somebody who has achieved top 5 on the competitive ladder is most likely in the top 2000 players to ever play the game. FORG1VEN has reached rank 1 on the ladder plenty of times and almost nobody would consider him the greatest European player ever.
While it is difficult to judge and rank players like this as it requires a lot of research, I would be comfortable saying he is at least the 15th best European player ever.
While some point to his lack of longevity, I do not consider this an important metric for rating AD carries. The idea behind why longevity is important in the first place is that it is an indicator you can succeed in various teams and metagames - which is less relevant for an AD carry as the role has barely changed since 2012. Another criticism is a lack of tournament wins - my issue with this criticism is that LoL is a team game, and there is more that goes into those wins than your own skill. Even AD carry legends like Doublelift and UZI had to play for over 4 years to win their first real titles.
Mathematical estimation
His z-score for LoL skill is 4.42, based on the fact there are 3 million accounts on the EUW server and he is in the top 15 players of all time.
His performance in Overwatch (~400 out of 1 million) indicates a z-score of 3.35. The mean and SD of somebody with this performance in Overwatch is roughly 1.49 and 0.9 - regressing his LoL performance to that metric yields an estimate of 140.
Arbitrary assessment: I personally consider him the most generally talented gamer in the world. Given that I think the general factor of intelligence and gaming correlate at 0.65, that gives him an (highly arbitrary and somewhat mathematical) estimate of 160. Based on his interviews and my assessment of his capabilities - this seems a little high to me. He’s probably somewhere closer to 145 or so.