Avid RISK fan, have played for 20+ years. I own 9 different RISK games, 3 PC and 6 board versions.
Being said, one of the best aspects of RISK is the political nature. Working deals with your opponents. That is completely lacking in this online version. There MUST be a chat. I have played games (live board game) where we can send notes to each other, which would explain a private chat option in the game. However, a global game chat where everyone see's what you're saying is an option as well since typically when you play the board game version everyone hears what you have to say to one another.
Knowing your opponent makes a huge difference in this game. Make a deal and break it, best believe everyone remembers that and it'll be hard pressed to find another ally again. Being online with 100's of opponents this isn't so easy. So I feel there must be an option to see a persons stats in regards to how many alliances they have broken by using the option AND by attacking. A way to rate the player might possibly work.
An option to select games that only meet a certain criteria really should be available. It's very difficult to scroll through all the games before it starts you back at 1. You should be able to at the least include filters of manual/auto, progressive/fixed, & time limit. It would be extra nice to also have a map preference, with the option to select multiple maps you're willing to play.
Eliminating cheaters is really hard, and a double edged sword. The easiest way to hinder them would be to show an exclamation mark in a player icon if they have played with someone in the same room. Clicking on the icon would show who they have played with in the room, how many times, and the win/loss record between them. Obviously many of us (myself being one) play with friends often. So to see the icon might not mean much. Seeing that one player wins 90-100% of the time though would be awfully fishy. This would also help to let players know "these two are friends, so watch out".