The polygonal reveal generally works well, as long as there are corners. As you can see, I was not patient enough to get the circular lobby completely within the lines. Note that the grayness is blackness for the players; the fog of war only shades things for the game master.

Because the Gods & Monsters maps are made with layers in Inkscape, they are easy to repurpose to other uses. For example, Rob Conley, several weeks ago, mentioned Roll20 over at Bat in the Attic. Roll20 accepts PNG and PDF images, and it honors transparency.

To create the player map, I unchecked visibility on everything except for the map itself: no grid, no key, no secret places.

Then, for the GM overlay, I unchecked everything except for the key. Because Roll20 honors transparency in PNG files, the map shows through.

The “fog of war” is especially useful: it lets you show only the specific part of the map they’re currently able to see. Fog of war is a setting in the page’s settings from the gear in the page toolbar. It’s only drawback is the lack of reveal shapes. There are only two reveal tools: rectangular and polygonal. So you can make any shape you want, as long as it has corners. This makes it a bit tricky to reveal full tower rooms or grand balconies without revealing the areas beyond the tower or balcony. You need to be careful setting up the polygon.

Very cool—with a caveat—is the map measurement tool. It quickly shows distances simply by drawing a line from start to finish. That’s as long as you aren’t looking at an overview of the entire map: the size of the measurement number scales down with the map, so if you set the map to be 20% size, the measurement number is also 20% size, practically unreadable.

The map measurement tool quickly calculates distances.

It has a dice language for setting up die rolls. For example, 4d6 drop the lowest is performed as either “/roll 4d6d1” (4d6, drop the lowest one) or “/roll 4d6k3” (4d6, keep the top three). I kind of like the “keep” option because it doesn’t duplicate the “d” and is thus easier to read. Common dice rolls can be set up as buttons for quick access. In the screenshot on this page, you can see three buttons in the lower left. One for surprise, one for attacking, and one for rolling all six abilities.

The system also lets you set the number of squares in the grid. Most of my maps are bigger than the default grid size. You can also set the size of the grid, in pixels or the size of each unit in pixels.

If I were running a Gods & Monsters game online, I’d seriously take a look at Roll20; it’s a snap to take layered maps and upload them so that the players see the map and you see the map and the key. Player handouts can be set up ahead of time as a “handout” and then dropped into a character’s journal, to be seen only by that character.

One useful tip, you can hit your own gear icon and “Re-Join as Player” to see what your players are seeing. It’s spooky to see the map with nothing showing but where they’ve already been!