Water Sort — free browser game

Goal: solve the puzzle by leaving every tube on screen either completely empty or filled with a single colour. First click the source tube (you'll know it's selected because it rises slightly), then click the target tube; the top layer of liquid flows across. A pour is only possible in two cases: the target tube is empty, or the target's top colour is the same as the source's top colour. Consecutive same-coloured layers stacked on top of each other flow together in a single move, but if there isn't enough room in the target, only as much as fits is poured; each tube holds at most 4 layers. If you made the wrong selection, you can deselect by clicking the same tube again or pressing Esc. If you make a mistake, undo the last move with Z (or Undo), reset the level from scratch with R, and once solved move to the next level with N. Tip: don't waste empty tubes hastily — use them as temporary storage; also, before pouring, check which tube the layer beneath that colour ends up in, so you can set up chained moves without getting stuck.