While I was in the Marines we played what we called Risk 2, we took a second Risk game and played it one of 2 ways;
The first was that the second board was a different planet and it could only be reached once a player got a full continent. Once that was achieved the 2nd planet would be filled by said player with one army from said continent each turn, but the other players would achieve, thru espionage, "space flight" in order of strength on the 6th, 7th , 8th turns from the time the first player got it.
the second way was to put the 2 boards next to each other and play with a double wide single planet. This could be altered by how we placed the board, the 4 options were side by side, top to top, top to bottom and bottom to bottom, We used grease pencil to mark the lines of contact because that wiped off after we were done.
We also played double board monopoly. First go around one board then the other. A monopoly consisted of the quantity needed for a single game. Park Place on both boards made a monopoly, or 3 Light blues from either or both boards counted, Extra monopolies started when you had more than an original monopoly, Parkplace from both and Boardwalk from one. Boy did the prices go up then. We used the money from 4 sets and had a dedicated banker. Utilities also worked, you could have 3 railroads on one board and 1 from the other giving you 4 which was a monopoly. OBTW we marked one board and all of its properities with a Big red magic marker x
