I think it might be on par with sports and music forums. Both are highly competitive niches, which makes them a lot more fun.
The gaming industry is a broad niche because it involves so many different games and consoles. This means there are plenty of areas to explore and cover within the niche.
The biggest gaming forums I think are:
Join the PC Gamer community to share your passion for gaming with people from around the world!
forums.pcgamer.com
The latest video game news, discussions, announcements, industry gossip, sales figures, bargains and reviews. The pulse of the gaming industry.
www.resetera.com
https://www.neoseeker.com/forums/pc/ - it’s still using vBulletin 3.