Varicella

Although David Whyld's review almost says it all, I wanted to express my opinion on why this game is awesome, and what is the best way to play it (yes, you have to be prepared: preparation will lead to a deep gaming pleasure, while getting to Varicella unprepared might lead some people to total frustration).

THE GAME:
The king is dead. Within your palace, all will happen, and you will have to plan your way to the throne. That is: get rid of all the opposition. Within 100 moves. You are a vile, treacherous man, and you will behave as such.

GET PREPARED:
You have a very limited amount of moves before Varicella ends, and you have to plan everything with a huge amount of accuracy. Personally, I totally hate games with time/move limits. But this was not the case. Because this game is wonderful. And because I was prepared.
You gotta think of yourself as a time voyager. Varicella is simply the body that you will evilly posses in your journey. Thus: you have a mission, but you also have time-voyager curiosities.
Begin by satisfying the curiosity. Dedicate a number of games just to the discovery of what happens in the palace, and when. It will not be boring at all, because the world you'll get immersed into, is a deep and fascinating one. And in it, a lot of things change during those 100 moves.
After you know what's going on, and possibly when, you can get on the puzzles/treacherous-plannings. Start by solving a puzzle a game. Then, when you think you have solved everything, put them in the right sequence for the final rush.
Other than that, if you're not a lover of draw-the-map-yourself, you might also want to download the map.

If played the right way, this game will totally capture you. The palace is rich and detailed. Almost everything is interactive. And, while some NPCs are quite interesting, others are totally fascinating. Plus, for once we have an IF where you play a vile, immoral, and clever character: and this adds a lot more depth and fun ;-)