An Icehouse set is a set of 60 square-based pyramids - 5 each of 3 different sizes in 4 different colours. Andrew Looney describes the Icehouse set as being like a pack of cards or a dominoes set - that is, not a game in itself, but the basis for a whole series of games. The set is sold as a kit - punched card pieces which can be assembled to form the pyramids, with a spare card of each colour to allow for mistakes. (It took me about 4 hours to put all the pyramids together!)
The main game played with these pieces, also called Icehouse, is both challenging and unique; each player starts with all 15 pieces of 1 colour in their 'reserve'. There are no turns in this game; players may place pieces as fast as they like, whenever they like, but may only place one piece at a
time. The game only ends when the last piece is played.
Pieces played on their bases are 'defending' pieces, and score points at the end of the game unless they have been 'iced' (additionally, all players must have at least one un-iced defending piece in play at any time, or they lose immediately, scoring 0 points - they may, however, continue to play pieces under certain circumstances, ...).
Attacking pieces are played on their sides, pointing at a defending piece. They score points at the end of the game if the defending piece they point at is 'iced'.
As I mentioned above, there are three sizes of pieces in an Icehouse set. Small pieces are worth 1 point, medium pieces 2 points, large pieces 3 points. A defending piece is iced if the points of the attacking pieces are more than the points of the defender. If there are so many pieces attacking
a defending piece that one can be removed while still leaving the defender iced, then the defender is said to be over-iced - the defending player may capture one of the surplus attacking pieces.
There is a fair amount of strategy in the game, once you get over the initial bewilderment - players may attempt to wall off their defending pieces with attacking pieces to prevent them being iced (called an ice fortress), but an attacking piece is never safe - other players may conspire to over-ice the
attacked piece, allowing capture of the original attacker, thus creating a hole in the fortress so the defending piece(s) inside can be iced. Since a player can't attack their own pieces, this requires cooperation between players, and negotiation is encouraged. Captured pieces may also be used to
advantage - the capturer can (and must) put them back into play, either as attackers or defenders; one possible strategy is to play a captured piece then immediately ice it, another strategy is to use the captured pieces to over-ice your own defenders, allowing you to capture more pieces, ...
Well, that's Icehouse; I haven't played the other five games that can be played with the icehouse set yet, but perusal of the rules suggest that they are skillful and original, if somewhat more conventional than Icehouse itself.
Note: Looney Labs have just produced a new version of the game - check their web site for details.