I have trying to do a mockup for a new forum (there are too few out there and tried to find another way to navigate. Right now it is read only and a bit unstable, but I do appreciate opinions about the navigation especially. It is developed so you can navigate easy on a mobile.
You have no keyboard focus indicators for your links so I have no idea where I am while tabbing through your menu.
Every link should have some sort of text/label. Right now your icon links do not have any and thus someone using a screen reader will have no idea what those links are for. In this case, because you are using the <img> tag you could use the alt attribute for the link text. https://www.sitepoint.com/15-rules-making-accessible-links/ (See rule 12)