Hi. The icons on the main page are from https://game-icons.net/ which are free under a CC license. (I am suddenly wondering if I remembered to put attribution on the image pages. I meant to but I may have forgotten.)
I used a square with rounded edges and the background colour 012e59 (same as our header on the wiki).
However, the logo in the wordmark (the shiny d12 floating over a plinth) was made by me. (Which is why it doesn't look as good as the others.) The fonts in the wordmark are free for commercial use and called Devinne Swash (possibly the same font from the title of Dungeon Crawl Classics? it's similar anyway) and Rise of Kingdom.
I'm not very invested in any of these, especially the wordmark. I consider them to just be what we're using for now rather than something to keep indefinitely.