This sort of puzzle, where solvers are tested on their ability to follow incomplete or otherwise complicated constructions, is often referred to as a Conundrum or Konundrum. In this case, solvers are given all the information, and this puzzle is just a test of their comprehension and ability to follow directions. This is easiest to do with a physical copy of the board game, but a wordy walkthrough is provided here.
The theming of the puzzle suggests the board game Clue (or Cluedo in the UK – the differences between the versions are immaterial for this puzzle). The first three paragraphs serve to set the scene and explain the rules of the puzzle. At this point MR. GREEN, MRS. WHITE, and the KNIFE are in the STUDY, PROFESSOR PLUM and the ROPE are in the HALL, COLONEL MUSTARD, MRS. PEACOCK, and MISS SCARLET are in the KITCHEN, the LEAD PIPE and REVOLVER are in the BALLROOM, the WRENCH is in the LOUNGE, and the CANDLESTICK is in the CONSERVATORY.
In the next turn, COLONEL MUSTARD moves to the STUDY, and MR. GREEN goes to the KITCHEN. MRS. WHITE arms herself with the KNIFE and moves to the HALL. MISS SCARLET and MRS. PEACOCK have no weapons to pick up, but both move to the BALLROOM.
Since MRS. WHITE is now holding the KNIFE in the same room as an unarmed PROFESSOR PLUM, she knocks him unconscious, and the KNIFE and PROFESSOR PLUM are removed from play. Write the letter F in the HALL.
In the next turn, MRS. WHITE picks up the ROPE. MRS. PEACOCK gets the LEAD PIPE and MISS SCARLET takes the REVOLVER. COLONEL MUSTARD moves to the CONSERVATORY and claims the CANDLESTICK, and MR. GREEN moves to the LOUNGE and gets the WRENCH. Everybody is armed, so no crimes are committed this turn.
Next, COLONEL MUSTARD with the CANDLESTICK moves to the LOUNGE, and MR. GREEN with the WRENCH goes to the CONSERVATORY.
There is only one pair of suspects in the same room, so at the end of the turn MRS. PEACOCK has the REVOLVER in the LIBRARY, and MISS SCARLET has the LEAD PIPE in the LIBRARY. The letter I is written in the LIBRARY.
The next clue references the KITCHEN, since it, the BALLROOM, and the DINING ROOM are empty. MR. GREEN with the WRENCH goes to the KITCHEN. COLONEL MUSTARD with the CANDLESTICK also reaches the KITCHEN. MRS. PEACOCK with the REVOLVER moves to the CONSERVATORY, MISS SCARLET with the LEAD PIPE goes to the BALLROOM, and MRS. WHITE with the ROPE ends up in the DINING ROOM. Since two armed suspects meet in the KITCHEN, write a T there.
MRS. PEACOCK leaves the REVOLVER in the CONSERVATORY and moves to the BILLIARD ROOM. MRS. WHITE drops the ROPE in the DINING ROOM and moves to the BALLROOM. There, an unarmed MRS. WHITE is knocked unconscious by MISS SCARLET with the LEAD PIPE. MRS. WHITE and the LEAD PIPE are removed from the game, and an I is written in the BALL ROOM.
COLONEL MUSTARD takes the CANDLESTICK to the BALLROOM, MRS. PEACOCK moves to the LIBRARY, and MISS SCARLET goes to the CONSERVATORY and then to the LOUNGE. At the end of the turn, no two suspects are in the same room, so an E is written in the LOUNGE.
There are unconscious bodies in the BALLROOM and the HALL, so MR. GREEN and the WRENCH move to the DINING ROOM, COLONEL MUSTARD takes the CANDLESTICK to the CONSERVATORY, MRS. PEACOCK goes to the BILLIARD ROOM, and MISS SCARLET enters the DINING ROOM. At the end of turn, MR. GREEN uses the WRENCH to knock MISS SCARLET unconscious in the DINING ROOM. MISS SCARLET and the WRENCH are removed from the game, and the DINING ROOM gets a C.
MR. GREEN is in the DINING ROOM along with the rope, so he remains unarmed and moves to the KITCHEN. COLONEL MUSTARD is in the CONSERVATORY with an unclaimed REVOLVER, so he keeps his CANDLESTICK and goes to the BILLIARD ROOM. MRS. PEACOCK is already in the BILLIARD ROOM, unarmed, so she gets knocked out by COLONEL MUSTARD with the CANDLESTICK. the CANDLESTICK and MRS. PEACOCK are removed from the game. An N is written in the BILLIARD ROOM.
By the penultimate turn, the only two rooms without weapons are the CONSERVATORY and the STUDY. Since the REVOLVER is in the CONSERVATORY, both remaining suspects rush toward that room. In one step, COLONEL MUSTARD reaches the CONSERVATORY and arms himself with the REVOLVER. MR. GREEN gets to the BALLROOM, but finds no weapon there with which to arm himself. (The one remaining weapon is the ROPE, currently in the DINING ROOM.) Write the letter O in the CONSERVATORY.
Since the STUDY is now the only room without a letter, MR. GREEN rushes there, where COLONEL MUSTARD knocks him unconscious with the REVOLVER. MR. GREEN and the REVOLVER are removed from the game, and the letter N is written in the STUDY.
Colonel Mustard may have knocked all the other guests out, but the puzzle asks what caused the death of Mr. Boddy. Reading the letters in the rooms clockwise starting in the library, spells out the answer, INFECTION. There was no murder done today.