The Key is a new game series from Haba offering competitive crime and puzzle-solving. Each of the three games (Sabotage at Lucky Llama Land, Theft in Cliffrock Villa, Murder at the Oakdale Club) offer a different scenario with nine different cases. Each case is based on a different combination of suspects, tools and crime location. But even if you have played all nine cases, you can play them again to optimise your way to solve the case.
Eric Martin from BGG News has taken a closer look at one of the games and played a review copy of Murder at the Oakdale Club:
I’ve now played The Key: Murder at the Oakdale Club a half-dozen times on a review copy from HABA, and the gameplay flows smoothly after your first game — not that you’ll always be correct, mind you. You can easily make false assumptions about something you see, and unless you draw additional evidence cards that cover the same material — which you’re trying to avoid doing to keep your evidence total low — you might miss the error because you’ll have enough evidence to be certain, but not enough to know that you’re wrong. That happens plenty of times in real life, and now you can experience that unpleasantness yourself, but thankfully with far smaller consequences.(Source: BGG Blog post)
He has written a blog post about the key games, explaining how the games work, but also published a Youtube video explaining everything in more detail: