One purchase, three attempts. A started team is an attempt. Only your first attempt lands on the leaderboard.
A case is chapters. Each chapter opens at a place everyone goes to, hands out one lead per detective, and closes with a lead that needs what everyone brought back. Nobody can run ahead: the next chapter opens when the team gets there.
Everyone has their own car. Pick 1–4 detectives; it locks when the case starts. On a team, each detective drives their own lead while the others drive theirs; every paper anyone finds goes into the team's locker, the whole team is told when a lead is found or a door opens, and riding along to a teammate's stop is free.
Teammates need no account. Share the join code or the link; up to three guests can sit at the table. Only the leader starts, pauses and submits.
Score. Right answers first, then fewer rides, then time. Going back to a place you have seen is free; a wrong gate code costs a ride; a hint on a lead costs one. The board is per team size.