Can you explain the main mechanics? Is it more abstract like P.I. or something more story driven and visceral?
The game is very story-driven and, yes, very visceral.
The game includes the following:
1.) 10 cases (a booklet for each case)
2.) 10 sets of newspapers, one for each case
3.) Directory booklet (like a yellow/white pages, with a list of names, locations, and businesses)
4.) Map of London
5.) Rule book
For each case, you take the corresponding booklet, read the case, and afterwards you begin to pursue leads based on the information of the case. Each lead might potentially direct you to another lead, and so on until you feel you've questioned enough leads to potentially solve the case. The related newspaper for the case can also generate leads as the newspaper might contain particulars related to the case that you may pursue.
I'll give you an example of one playthrough using a case I'll make up.
Case #100: A neogafer, named TheHorror, was riding his bike on Liverpool Street, near the intersection of George's Road, when suddenly a tomato hit his head, causing TheHorror to fall off his bike and onto the pavement, wounding his head in the process. A witness, EvilLore, says the tomato-thrower wore a long overcoat and top hat but he raced away from the scene before EvilLore could take a solid look at him.
After all the players have had a chance to read the case, they decide who goes first. The following is based on competitive setup (not group play). The difference is that, in a competitive setup, each player may pursue leads and handle clues separately from the other player; in a group game, all players work together and share information/notes/clues, thus eliminating the concept of "turns."
Player 1: Well, the first thing Player 1 would probably do is try to question EvilLore, the sole witness, some more, so Player 1 grabs the directory booklet and searches for EvilLore's name, and gets his location (3E). Player 1 then grabs the Case Book and searches for 3E, and after finding it in the case book, proceeds to read the corresponding information quietly to him/herself. This information provided by EvilLore in the case book may yield even more clues, more information that Player 1 will jot down for future reference.
Since each player is allowed to only follow ONE lead a turn, Player 1's turn is over since EvilLore is considered a lead.
Player 2: Player 2 may decide either to pursue the same lead as EvilLore (if this were a cooperative game, Player 2 wouldn't need to since Player 1 has already done so on the previous turn and has already shared his/her information with Player 2), but instead Player 2 elects to refer to the map of London and investigate the scene of the crime (intersection of Liverpool and George). Having located the intersection (4WC), Player 2 goes into the case book and searches for 4WC, then reads the corresponding information to him/herself, taking all the necessary notes.
That concludes Player 2's turn. Now, on to Player 3...
Player 3: Player 3 has the option of pursuing either of the aforementioned leads already exhausted by Players 1 and 2 (Player 3 would get the same information), but instead Player 3 remembers seeing something about a disgruntled tomato vendor in the newspaper and elects to pursue that lead instead. So Player 3 finds the name of the disgruntled tomato vendor from the newspaper, tracks the vendor's name in the directory booklet, gets the vendor's location (7NW), takes the case book and searches for 7W, then reads the information, takes down notes.
That's Player 3's lead, so his turn ends.
This VERY BASIC example reflect a competitive setup, so none of the players know exactly what information (clues and so forth) the other players' have, unless they use their turn to access the same leads (which happens more so than not), but even then each player might not pick up the same, minute clues each lead yields. Since, in this example, none of the players have opted to pursue the same leads, everyone has a unique set of information. However, this will change during the course of the investigation because everyone will eventually exhaust every possible lead in a case, and it'll be up to each player to come up with their own solution - through deduction - for the case.
I hope I didn't make it sound more complicated that it really is. There are no game pieces, coins, or any of that stuff associated with this game. The game revolves around reading, taking down notes, and formulating a hypothesis once all evidence and leads have been pursued.
It's very simple, but very challenging and rewarding.