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 rather than colour is the resource you are really managing.
A hundred and fifty-four rule sets cover guide lanes, on by default, that give every colour a bottle of its own to finish in with the assignment drawn at random, hidden layers, rainbow liquid that matches anything or binds to the first colour it touches, iced layers, unstable layers burning a fuse counted in pours, sealed and shut bottles, unequal glasses, blocked capacity, linked pairs, reverse gravity, tubes open at both ends and benches where pouring follows a ring, line or star. Two hundred and sixty puzzles ship with a machine-verified winning line, sixty of them guide-lane challenges, and the par is a proved optimum on two hundred and four; where the search could not close, the board says so and offers no star rating rather than one nobody could fail.
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 with its own pouring rules attached. The assistant runs a real solver and says which kind of answer it has, a proved finish with the pour count or a judged move when the position is too large to settle, and it will explain its reasoning on request.
Twenty glassware shapes, ten liquid themes, four symbol sets for reading the bench without relying on colour, thirty bench looks with a colour editor, twelve save slots with autosave, JSON in and out, five languages.