by urjustintime
If your 7-year old plays Risk fine, then he'll probably play this just fine. Just make sure he understands the new rules about special powers, cards, and how you start in just one territory.I have only played with 5 players and what I can tell is that 5 player games will go faster than 3 player games, as capturing other players' headquarters is really what the game is all about. With 5 players, everyone is very close together so it doesn't take much for someone to drive armies into a couple HQs and win.
I haven't actually tried it with 3 players but I imagine that the person who wins will end up controlling most of the board, making it more like regular Risk.
And as someone stated earlier, you can have different numbers of players for each game. So you can give it a try with 3, then if you decide more players would be fun, find some for your second game!