Germany Airsoft Laws
Airsoft guns under 0.5 joule are considered toy guns and can be freely sold to all persons above 3 years of age. Distributors agreed to raise the limit to least 14 years of age. All airsoft guns between 0.5 joule and 7.5 joule must be bolt-action or semiautomatic only and can only be sold to people 18 years or older. These are considered "free" firearms, as a result: Sales of guns of more than 0.5 joule are allowed only in weapon shops. Guns must be marked with the trader's weapon abbreviation and a F-in-a-pentagon mark as well as the airsoft gun caliber (such as 6 mm BB). Target illuminating devices and lasers may not be attached to guns but are legal otherwise. For example: possession of a flashlight is allowed, even shooting with the flashlight in one hand and the gun in the other; but attaching it via mount ring to the rail system of a gun is not. Devices made specifically for the purpose of being attached to a gun (like certain flashlights with integrated foregrip for mil-spec rail) are prohibited.
While the possession of airsoft guns is allowed, the actual use in a game is (at least) hotly debated. For sure, most players using guns with more than 0.5 joule muzzle energy leave Germany to play in countries like France, Belgium, Denmark or the Czech Republic.
More information can be found at Airsoft FAQ on laws in Germany, which covers more complicated issues like the "Kleiner Waffenschein", issues with the OWiG §118 in Bavaria and a definition of the term "combat shooting".