Pour layered liquid between bottles until every colour stands alone. The whole top run of one colour travels together, and a pour that will not all fit sends across only what fits, so free space — not colour — is the resource you are really managing.
A hundred and fifty-four rule sets cover guide lanes that give every colour a bottle of its own to finish in, hidden layers, rainbow liquid that matches anything, iced layers, unstable layers burning a fuse counted in pours, sealed bottles, unequal glasses, blocked capacity, linked pairs, reverse gravity, tubes open at both ends, and racks where pouring follows a ring, line or star. Two hundred and sixty puzzles ship with a machine-verified winning line, and a par that is a proved optimum wherever the search could close; where it could not, the board says so and offers no star rating rather than one nobody could fail. The assistant runs a real solver and says which kind of answer it has — a proved finish with the move count, or a judged move when the position is too large to settle. A bench builder lets you paint your own board layer by layer, hand it to the same solver, and keep it alongside the built-in puzzles. Twenty glassware styles, four symbol sets for reading the bench without relying on colour, thirty rack looks with a colour editor, twelve save slots with autosave, JSON in and out, five languages.