In the swinging crowd you mixed with, six of the 24 possible partners was HIV positive. This means that, in this game, you had a 1/4 chance of choosing an HIV positive partner. The chances were the same whether you chose women or men as your partners.
In the game, even if you chose an HIV positive partner, you would not necessarily get HIV every time. Just like in real life, it depended on your luck and the type of encounter you had. In this game your chances were 1/3 of getting HIV from a positive partner. This is because 1/3 of the encounters you selected led to HIV.
So your chances of getting HIV from any given encounter with a partner of your choice were (1/4 partners was positive) times (1/3 encounters with positive partners led to HIV) = 1/12. This means, that for 12 plays, the chances were one would lead to HIV.
How was your luck? How many encounters did you have without getting HIV?
The HIV Positive Rate varies from group to group. In the United States, less than 1/100 persons has tested HIV positive; however, there are probably more people with HIV who have not been tested; among certain groups, drug users, people who swing, the rates are probably somewhat higher!
