So, according to Bumdi, here's the list of confirmed members of The Genius 3 so far:

1) Kim Jung Hoon - he's the guy from Goong! Haven't seen him in a long time, so let's see how this goes ;)

2) Kang Yong Suk - apparently, people don't really like him from Sseul Jeon, but he was alright in Crime Scene, so I'm actually quite excited to see him here :)

3) Lee Jong Bum - I don't know much about him, apart from the fact that he's a webtoon artist (like Kim Poong from S1) and that he hosts a radio show

4) Ha Yeon Joo - she's an actress, but I haven't seen her in any of her works. Let's see what she got!

5) Nam Hweejong - returning from S2. I'm actually looking forward to see how much he's going to change after what happened to him in S2... Well, hope he's learnt that no matter how high his IQ, it doesn't solve everything...

6) Jang Dong Min - unconfirmed - he said so himself on the radio, but nothing from the PDs yet... 

So, that leaves us with 7-8 free spots... I'm really hoping for some other people from S1 and S2 to return. Kong should come back, because it's just so fun to see him in the game! Or my other favorites could come back, like Kim Kyungran, Cha Yooram, or Cha Simple :D