Disavowal: These ideas are purely for people above 18 years of age. Any one below that age is requested not to try to host these parties without parental guidance (which I can predict, you will not get)! Hosts of the party have to make sure that adequate expert guidance is available (when needed).
So, since you have clicked the title, we are assuming you are old enough to deal with your fears. Many people are of the opinion that after the age of 16, birthday parties are nonexistent. Well, we believe in challenging the tradition. You can have a party even after your 'legal age'. You could try a 'killer party' with your fraternity brothers or sisters.
But instead of pretty pink and beautiful blues, you could go for Fear Factor. You must have already figured out how to make the theme apparent. But, what about the games (or challenges)? It would be a welcome change to do something other than drinking, dancing, and sitting around by the fireplace.
Rule: Make sure everyone is informed of the theme; surprises can ruin these games!
You can hire a team of extreme sport experts and ask them to manage the event from the terrace of your building or at any location that is feasible. This game is best played before nightfall, the fun is unbelievable when you can see the ground!
Whenever a person loses his/her balance, all the others present there get to give that person a task to do (maybe one task each). It can be absolutely anything. The game can go on for hours and the tasks can range from being difficult, to disgusting, to notorious, to simply impossible, but they have to be completed. Sounds fun?
Fear factor parties can be fun. But, the host has to make sure that no one's sentiments are hurt. All involved have to take the games and challenges in the right spirit and attitude. Party on!!