There was a “hidden forums” plugin, but it’s from a while ago:
https://bbpress.org/plugins/topic/hidden-forums/page/6/
There was also “read only forums”:
https://bbpress.org/plugins/topic/read-only-forums/
Maybe one will still work or give you ideas for your own plugin.
Neither of them have the features i’m looking for, and I’m way too stupid to think about coding a plugin, I guess I will have to give up on the idea.
Thanks anyway
You could do this in the theme files.
In topic.php, around line 35 where the topic posts are listed, check if they’re logged in.
e.g
<?php if ( bb_is_user_logged_in() ) { ?>
<?php foreach ($posts as $bb_post) : $del_class = post_del_class(); ?>
<li id="post-<?php post_id(); ?>"<?php alt_class('post', $del_class); ?>>
<?php bb_post_template(); ?>
</li>
<?php endforeach; ?>
<?php } else { ?>
<li>Sorry, you must be logged in to view this - register now!</li>
<?php } ?>