I’m not sure what it involves for Risk but I’d assume they are all pretty similar. The case study is a problem that you’re given and you have to read it and analyse what the problem is and give solutions/suggestions. If it’s to do with a Risk job, maybe you’d have to identify risks. It will be just you alone and you’ll have to present it to someone giving reasons to why you say what you say. Be prepared for questions, sometimes they may be awkward but they’ll be testing if they can catch you out so display your confidence.
The group exercise normally includes 4 or 5 people. You are all given different pieces and you have to communicate verbally what is on that piece but you can’t read the other persons paper or look at it. You will all need to do this else you won’t be able to solve the puzzle so prompt people to reread their information if you feel their is data missing. Remember to communicate your piece of puzzle over to others. Don’t just read it but summarise all the essential points. I don’t think you can really prepare for this, just be yourself but make sure you contribute but don’t be overly bossy. Make sure you listen and give your own suggestions. Don’t be afraid to ask someone why they chose something if you feel they are wrong.
I have no idea what the role play is about or what it involves. Perhaps someone on the forum will be able to tell you more about it.
Best of luck for your interview and let us know how it goes.