Kamaril, here is the wiki page for the fog of war and about the page settings for the fog of war. As Vince has stated, you can adjust the GM Opacity with the slider, try the CTRL+L, or you can rejoin as a player to see what the players see. Wiki page quoted The fog appears as a solid black area to players, but for the GM it's a semi-transparent layer. If you'd like to adjust how dark the fog appears to you (handy for dark maps where it's hard to tell where it is) use the "GM Opacity" slider to adjust how transparent or opaque it appears. Simply slide the slider to the left to make the fog lighter, or to the right to make it darker. If the slider is all the way to the left, the fog will be completely invisible, and if it's all the way right, it will be completely solid.
