I would just like to mention that this will be a VERY slow game if we only have a random chance of being able to attack someone. Risk was based on how many armies you could afford to spend, and the more land you owned, the more power you controlled by dint of earning more armies every turn. I think that rather than simply having a random chance of conquering a territory or two, you should have the ability to conquer territories based on this random chance modified by how many territories you control. Risk also had the wild card (quite literally!) in the sense that in a turn where you conquered land, you got a card with one of three types of army on it (infantry, cannon, or cavalry) or all three (a wildcard, acts as one of any). When you had a set of three of the same kind, or a set of all three, you could trade them in for more armies. Every time someone did this, they got more armies than the last person, up to a point.
A decent suggestion is that rather than having a small chance of conquering land, you can declare five territories in order that you would like to conquer (by color) and your roll for the turn (as in the post where you declared them) determines which ones you get. (i.e. a six gets all five, a one gets none, a two gets the territory whose color you marked as number one. (the colors can't be an existing empire, they have to be unused to differentiate) and the game moves on from there)
tl;dr I don't like a game of luck, I would rather it was a game of skill augmented by luck.
