Insanely addictive Japanese puzzle game for Playstation. The USA version is called Devil Dice. The name XI [sai] is nice because it hints at the Japanese word for dice, saikoro, and has other nifty interpretations as well.
Game play works as follows: a square grid (like an unmarked scrabble board) is littered with dice (every square can contain a single die or be empty), and the player controls a small demon who can move dice around. When the demon is on top of a die, he can move it around by logrolling or he can walk to adjacent dice, thereby having access to the entire board. When he is on the board ("on ground level") he can push dice around, in the style of Sokoban. Periodically, new dice rise out of the board, and the player can move from ground level to dice level by standing on one of these as it moves up. He can move from dice level to ground level by standing on a die that is sinking because it has just been cleared. Dice are cleared when a move results in at least two adjacent dice showing "2", or at least three adjacent dice showing "3", et cetera. The game is over when the entire board fills up with dice. The object is to get as many points as possible (by clearing in an efficient manner) before this happens. Games typically last over an hour.
Scoring works as follows:
- When dice are cleared: Score += (number of dice removed) * (value showing on each die removed). For example, clearing five "5"s would yield 5 * 5 = 25 points.
- When dice of the same type as those sinking into the board are made adjacent to the ones sinking: Score += (value of sinking dice) * (value of added dice). For example, if six "6"s are sinking, and the player adds another "6" to the chain, he would recieve another 6 * 36 = 216 points. This is called chain clearing, and is where most of the score usually comes from.
The game also includes other modes, such as two-player cooperative "exhibition" or competitive "battles," up to five-player competitive "wars," and a "puzzle" mode which illustrates the basic strategies of successful game play.
The Japanese advertising campaign featured a commercial in which a businessman working in a cubicle suddenly sees all the cubicles around him rotate into formation and sink into the floor. This is a pretty accurate description of how addictive this game is. It infects players' thoughts, even their dreams. I was stuck on puzzle 92 for days before bolting from my bed one night and turning on the playstation to try out the solution that had come to me in a very strange dream. When it turned out to be the correct solution, I knew I was hopelessly addicted. | 
