Could you not think of a riddle that was not about killing?
At least it was just a riddle. What I don't understand is why people post ghastly stories like the man killing children. What's the point of spreading that horror?
You did not specify whether "You" is a part of the 34 people or not. If "You" is a part, then there are 34 people. If "You is separate from the "34 people, then there are 35 people. You also never said wheth the "There are 34 people" means that there are 34 people in the room. You only said that "there are 34 people. These people could be anywhere since you never said where they were. Then you said, "You kill 30." You never said whether the 30 "you kill" are a part of the "There are 34 people."