Building play by forum roleplaying games (rpg pbf)

Hi, I’m looking to have modern forum built for online rpg games (all kinds, fantasy, horror, modern, etc.) and discussions, etc., with built in features for playing sessions (virtual tabletop where registered users create playing characters and within the game threads post as avatars of their PCs).

I prefer it not being vBulletin. Open source would be best to avoid future costs. Old forum is vBulletin but is very outdated. I’m looking for something different than vBulletin

If interested I can provide link to existing old forum to visualize what I’m trying to accomplish. The link is www.lastinn.info however, to see how the game panel looks like one must register as user. Guests will see just the posts not different from discussion topics