The font files are located in the ARC file Fonts.arc (Titan Quest/Resources/). There are three files with the extension .fnt: * Albertus MT Light.fnt * Albertus MT.fnt * Arial.fnt They are just renamed truetype fonts. Use ARC Explorer to extract them. To use your own fonts in game, rename the desired font files to these names, and create a new Fonts.arc file with the Archivetool utility and then backup your original Fonts.arc file before replacing it with the new one.