Without giving the puzzle away in the post office in "Deponia: The Complete Journey", it is clear that depending on whether the cats are sped up or slowed down, various pigeon holes are chosen to expedite the packages. It is also observable that each of the two cats in the post office have three different speeds: slow, medium and fast. An easy way to approach such situations in adventure games is to construct a table with all the possible settings of the items.

Depending on how fast or slow the cats, from left to right, "Tabby" and "Whitey" react, the packages are routed out through different pigeon holes. Here is the table summarizing the effect of the settings.

Regardless of anything else, these are the total number of possible settings that can be made using the two cats and by speeding or slowing them down, such that the next step would be to investigate what each setting implies for the rest of the puzzle.

Pedantically, the total number of permutations (with repetitions) is given by where is the number of items (fast, medium, slow) and is the number of items to select (two cats) resulting in total settings.

In the second chapter, in order to be able to lift Goal successfully and place her on the carriage, you are told you need to calm down and, for that purpose, to ask Doc for advice. Unfortunately, the procedure required to advance is counter-intuitive especially if the player tends to ignore Doc while Doc turns to the horizon and meditates. One must place the cursor on the horizon and then right-click when Doc tells the player to focus on the horizon. The result thereof will be a series of letters appearing on the horizon that Doc looks at in sequence in order to reveal a code.

After going back to the crane, if the player right-clicks the booze in the inventory, nothing significant will happen and the game will not progress. Similarly, just looking at the horizon in the crane scene will not help at all. Another thing is that using the bottle on all the interactibles will not help at all. In fact, the booze bottle is somewhat of a red herring, even if it can be used, given that in order to progress the player does not have to interact with the bottle at all, except when stealing the booze from Doc.

Instead, after Doc's instructions, the player must go back to the crane, climb into the crane and sit down, and only then right-click the horizon. If successful, a series of letters will appear on the horizon and the player must select the same combination of letters that Doc looked at during the meditation session. If the correct combination is chosen, then some of the alcohol will be consumed and Goal will be lifted onto the cart.