Germany is very strict in that regard (violence. Sex isn't a problem, unlike the USA for example) any many german gamers (like me!
) buy their games from Switzerland to get around it.
Switzerland will get stricter laws soon too, that's the real ****.
Is it actually true, that you cant kill people in computer games in Germany?
That the blood has to be green, or the people you are shooting have to be robots or something?
Or is that all complete bull****
Not excactly, it depends on the game or to be more precise, the context.
Soldier of Fortune 2 for instance was castrated totally, the enemy soldiers have been replaced by androids ( who look like humans and have green/ yellow blood ( oil ).
Max Payne for instance was released full, then shortly after it was indexed and re-released as German version
because the reason Max Payne is killing people is not to defend someone, his motivation is vengeance.
In most cases the blood gets removed, most games where you have to kill people or innocents can be killed for fun gets castrated ( carmaggedon ) or indexed, so only adults can buy them.
Games where you can massaker or torture humans are on the index before release

as well as games that show Nazi symbols.
Sex or nudity isn't a big problem, also killing Aliens isn't a problem either, no matter how bloody it looks, you can splatter the guts of a Alien across the floor and paint the room with it's blood.
This will get changed sooner or later, which sucks.