I was curious what those big numbers in green that are on the
Daedalic and (soon to be published)
Mamba boxed versions of Machinarium were and found out that they were
PEGI (Pan-European Game Information) ratings. They're supposed to "help European parents make informed decisions on buying computer games".
So, the first boxed version to come out was Daedalic's and Machinarium got a "7" (meaning: "Any game that would normally be rated at 3 but contains some possibly frightening scenes or sounds may be considered suitable in this category. Some scenes of partial nudity may be permitted but never in a sexual context." Which seemed a bit harsh...
But when it comes out in the U.K. it only gets a "3" rating. (meaning: "The content of games given this rating is considered suitable for all age groups. Some violence in a comical context (typically Bugs Bunny or Tom & Jerry cartoon-like forms of violence) is acceptable. The child should not be able to associate the character on the screen with real life characters, they should be totally fantasy. The game should not contain any sounds or pictures that are likely to scare or frighten young children. No bad language should be heard and there should be no scenes containing nudity nor any reference to sexual activity."
~Whew!~