Time travel would seem to be a fairly intractable subject for a game. After all, paradoxes are a major issue, and the sheer variety of potential outcomes are a challenge, at least if you posit that changing the time stream is at all feasible (and if you don't, then time travel is nothing more than historical tourism). That's one reason that Chrononauts is such a clever design; it tackles the problem head-on, producing something quite satisfying (and even instructional for younger players without much knowledge of history) with what is, when you come down to it, a remarkably simple and quite clever system.
You begin the game by laying out the 32 historical event cards, in temporal order; they begin in 1865 (Lincoln Assassinated), and end in 1999 (Columbine High School Massacre). Each card has two sides; initially, all are placed with the historical (in our world) event as it happened. During the game, events can be flipped by the play of Inverter cards; thus, "Lincoln Assassinated" can be flipped to the reverse side, which reads "Lincoln Wounded." Some cards have "Ripples" which result in other cards being flipped--thus if Lincoln was merely wounded, the 1868 and 1974 cards are also flipped -- Andrew Johnson isn't impeached (presumably he wasn't President in 1868), and Nixon didn't resign (possibly because no president had been previously impeached).
Some cards, on their reverse, merely read "Paradox," meaning that this change results in a Paradox--and if too many paradoxes accumulate (13 to be precise), everyone loses, because the time stream has gotten too weird to survive.
At the beginning of the game, each player is dealt an ID card, and a Mission card; these provide two of the three ways a player may win. Your ID card determines what version of the timeline you come from (my favorite is the intelligent cockroach from the future who tries to ensure that the Cuban Missile Crisis ends in World War III so that humanity is destroyed and his people can ultimately evolve). Each ID card lists three events; one way to win is by manipulating the time stream so that it corresponds to the state from which you come, allowing you to go home. The Mission card lists three "artifacts"; if you collect the three named on your card, you win by fulfilling your Mission.
At the beginning of the game, each player is dealt three cards from the regular deck, and during your turn, you draw one and play or discard one. In addition to Inverter cards (which let you flip cards in the timeline), there are Artifacts which you play to retrieve from time; Actions and Timewarps, which you play and follow the instructions on the card (Timewarps can be played at any time, Actions only during your turn); and Patches. Patches are historical events that you can play on top of a particular Paradox to "patch" the time-stream and resolve the Paradox; thus, for example, if "Nixon Resigns" is currently in Paradox, then you can "Patch" the timestream with "President King takes Office" (Martin Luther King becomes first black president following impeachment of Nixon).
Which leads to the third way you may win: Each time you succeed in patching the time line, you draw an extra card, which permanently increases the number of cards you may hold in your hand from the starting level of three. If, at the end of your turn, you have 10 cards in your hand (implying that you've patched the timeline 7 times), you also win.
Chrononauts takes less than an hour to play, and is an excellent pick-up game for a party or convention setting. If it has a flaw, it's that when taken seriously as a game of strategy, it loses, in essence, much of the humor that makes it enjoyable. That is, to play it seriously, you need to memorize what each of the Missions and ID cards say, then try to guess which one each of your opponents possesses, and try to thwart them from achieving their objectives. But if you've learned the game that deeply, then you are also not likely to be surprised by an amusing twist to the timeline, since you know what's feasible during play. In other words, to some degree, mastery of the game diminishes its enjoyability, which would surely not be true of an ideal game.
Nonetheless, it's a highly imaginative design, and worthy of study as such.
This game has a great
This game has a great concept... but I found the gameplay to be a bit slow. As you said, in order to formulate a strategy, you've gotta memorize all those damn cards and their effects!
Setup takes forever, too. And the learning curve is kind of rough.
Nitpicking the review
Little things I'd like to correct, from having played the game.
-To change time so that Nixon does not resign, you must first change time to prevent the assasinations of both Lincoln and Kennedy.
-Timewarps can NOT be played at any time, the distinction between actions and timewarps is in fact that timewarps have more restrictions on them. The timewarp "rewind" allows you to take a card out of the discard pile and has the restriction that it cannot be another timewarp that you take, and the only card that can be played on someone else's turn is the timewarp "Memo from your future self" which can be used to block someone else's card.
-Finally, it is possible to win the "10 cards in hand" win condition without patching the timestream 7 times (although that is the most straightforward way of doing it). There exist actions in the game that allow you to "sell an artifact" and get more cards that way, just because an artifact isn't on your mission doesn't mean it's not super-valuable to the right buyer!
This last bit isn't a correction but an addition. You mention at the end of the review that once you master the game it starts to lose its humor. I would say that the way to handle this is to treat your actions as mild, vague, time-travel roleplays. For example, instead of saying "I'm flipping 1865 with the Prevent Assasination card" or even "I'm preventing Lincoln's assasination, rippling this and this" you could make up a story segment having nothing to do with the strategy itself, like "I travel back in time to just after the bullet hit Lincoln and use my future technologies to ensure that he survives." These short fictions are encouraged by the descriptions in the rulebook and the backstories on the IDs and Missions.
It's probably not a good idea to go overboard constructing stories, but I remember in one game I played, we (the players) kept assasinating and then saving Hitler (as he was opening the Olympics in '36) and I found the situation to regain its humor when I imagined three time travelers in fancy high-tech body armor fighting over a 6-shooter as Hitler walks past them obliviously.