The software handles all "forums" in one view by default. You can use categories to split it into subforums. An User can then pick a category and will see only threads from it.

There are some threads in this forum, where the installation of more than one forum on only one webspace is described. One very old thread picks some issues and offers solutions or this one or that one too. Try the search function i.e. with several forums or with multiple forums Read it and ask again if needed.

Tschö, Auge

Thanks for reply Auge. Actually I know there is a category filter. What I want is a sub-forum feature which look like this.

My site is mainly about gaming. For ps3 alone there are already thousands titles there. now comes the ps4 titles. I can't keep add categories in MLF for each game, which will increase the number of entries in the top-right drop-down menu, who want to navigate a drop down menu has thousands entries.

So I want to divide them into a A~Z subforums which can be selected from the main forum index page.
then divide them into a 2nd tier subforum named by each game's title. it kinda like directory management system in our pc.

I know the project is huge and very complexed just by looking at the 10,000+ lines of source code. I'm overwhelmed at least. Although I'm a noob in coding. just finished beginner php/mysql class this fall.
you guys did a great job layout the huge structure. Is it possible for MLF future update supporting the subforum feature? or I'm meowing at the wrong fish?

Another suggestion is: most ppl judges a product by it's look on first impression. My psn friends who visited my forum site said it look a bit messy. it took me a long while to figure out how to change the default looking to a cleaner table view.
in phpmyadmin interface type sql command:
UPDATE mlf_settings SET value = '1' WHERE name='default_view';
UPDATE mlf_settings SET value = '1' WHERE name='fold_threads';

#so maybe in future release change the following lines in install.sql file?
INSERT INTO mlf2_settings VALUES ('default_view', '1');
INSERT INTO mlf2_settings VALUES ('fold_threads', '1');