the minimum number of pyramids to be considered an Icehouse set
This format was created based on the description of Icehouse in The Empty City, which also defined the stash. As Icehouse is best as a four player game, an Icehouse set was quickly defined as four stashes, and is the common format used in the International Icehouse Tournament.
Pyramids were sold by the Icehouse set from 1992 to 2002. Xyloid pieces and paper pieces were sold in complete four-stash sets. The hollow KLON pieces debuted on the market in 1999 as "Icehouse: The Martian Chess Set", which was the sole sales product for Icehouse pieces until solitary monochrome stashes were made available in 2002.
Subsequent to the "Treehouse Revolution," pyramids have been sold in 5-color Rainbow or Xeno stashes (with the exception of Pink Treehouse). In order to create the traditional set of four monochrome stashes, it has therefore become necessary to assemble five Rainbow or Xeno stashes. Accordingly, some games have developed to a new default 5HOUSE standard, while others have been deliberately angled toward a reduced 3House Set of five colors with three trios each, or even the "IceDice Set" of five colors with two trios each. A full set of monochrome stashes spanning both Rainbow and Xeno color schemes is a 10HOUSE set.