Jigsaw

A whirlwind tour of the 20th century. Hunt for the jigsaw pieces that allow you to travel trough time, following a charming stranger who wants to "improve" history. Huge, difficult, exceptionally well-crafted. Lots of detailed research went into this game. The environment is highly interactive, with some extremely detailed gadgets (such as Alan Turing's Enigma machine.) Surprisingly enough, Mr. Nelson also found time to include some romance - and the love interest is that charming stranger whose plans you're foiling.

The game is divided into partially-ordered chapters, which are mostly, but not entirely, self-contained. Trinity's influence is obvious in the layout: a central strange and fantastic land, from which you can temporarily escape to the past.

Three warnings: Some of the puzzles are very difficult indeed (one requires elementary knowledge of Proust!), many of the chapters have time limits, and it is possible to lock yourself out of victory without realizing it. (For that last point: The Kaldecki Detector found on the Titanic helps a lot.) Has a crucial dependence on character graphics.