Have there been any simul round-robin games? It occurred to me that it would be possible to have a match in which, say, each of 10 players play each other simultaneously twice. That is, if a regular simul match is a line of boards, this would be a grid, with each player playing black along one row, and white along a column. (The intersection of their row and column would obviously not be played...) Doing it online would simplify things a lot.

It seems like it would be a pretty interesting test of abilities, and solve the usual one-sided nature of simul matches.

Has this been done? What's the common term for it?
Although I've never seen such a simul in action, I've heard of a similar concept before. The person who explained it to me called it something like "walking clock simul", but I doubt if there is an official name.
He applied it to a single round-robin (instead of a double round-robin) and a line of boards (instead of a grid), but the idea remains the same.

In any case, for N players, the number of required boards is N*(N-1)/2 for a single round-robin or N*(N-1) for a double round-robin.

For 4 players (A, B, C, D), the pairings of a single round-robin could look like this: 


A - B
C - D
D - A
B - C
D - B
A - C


In his format, the players would walk in the same direction (for instance clockwise) around the boards.

By the way, it is also possible to apply the idea to Swiss tournaments. For N players and M rounds, the number of necessary boards is M*N/2. Note that a single round-robin can be seen as a Swiss tournament with M = N-1.