Anywhere Board Games (ABG) is an open source web app for playing board games online in real time. The interface is drag-and-drop based with a context menu for special operations, like rotating a piece or changing (flipping) its state (face).
Users can provide .abg files (JSON format) to the server in order to describe pieces, their positions, and image URLs of what they pieces should look like in each state. Pieces can be added to a game in progress, and the game state can be saved as a .abg file for future use, so the game board is also a game creation tool.
Users need to run their own servers (unlike SDG, ABG does not run servers for you to play on). The Windows version of ABG comes with a launcher for an Apache server (this is the only version I've tested so far). Clients can then connect with browsers via IP address (the default port for the Windows version is 8080).
You can download my .abg file for Homeworlds using the links below. I plan to make several similar versions to include different features (like colorblind-friendly pieces). I will list them here as they are created.
You should right click on the link and choose "Save link/target as..." You can open the file once you are connected to an ABG server through a browser.
These boards have extra components like a timer and system labels. The turn timer can be reset for the next player by "flipping" it. The system labels resemble the ones used in Homeworlds Theater. You can delete these extras if you don't like them.
On these boards, the pieces have extra "faces" for quick rotations. You can just "flip" the pieces to change ownership.
Most piece actions are pretty easy to figure out (click for a context menu of options like "rotate," click and drag to move). There are modifier keys for multiple piece dragging explained here.
Here are some undocumented things that I found with experimentation.