I think whether God exists, whether its influence is visible in the world, and in which way he differs from a nonexistent God are interesting questions, but in this case we have just assumed that he exists and has influence in our 4 (or 11) dimensions. Otherwise he could not be put before a court.

A human court can not physically punish an omnipotent god, but can judge him morally, and can thus in some sense very well inflict the ultimate punishment on him. Besides, rumors are that a god dies as soon as all his believers are died out.

I must also mention, to avoid misunderstandings, that this God before the ICC is not the Christian god. The usual Christian god, as believed by the majority of Christians, has not inflicted death upon Adam nor allowed the earth quake of Lisboa. He has not directly created man and has no direct influence on earth, so he's not responsible for natural death and disasters. Thus you can't catch him red-handed and drag him before a court.

However the God before the ICC is the US-fundamentalist God. As I've learned, fundamentalists believe their God has inflicted death and suffering as a revenge for Adam's disobedience, called the original "sin". Maybe someone can correct me if I'm wrong here. As the fundamentalist God can cause or prevent disasters at will, the question the court has to decide is not whether God is responsible or not. The question is indeed, as Nitro pointed out, whether the killing was murder or not.

Killing is not murder in case of a 'just cause', like self-defense, a war, or a just law. But war or law can not always excuse killing people, as we know at least since the Nuremberg trials. Saddam also killed his victims by declaring war on them, or by law, or as a punishment for rebellion and disobedience, but this didn't help him before the court.

So the question is whether God had a 'just cause' for his killings. It not, it was murder, it's as simple as that. If he just says: "They died because of their disobedience to me", then he must also explain why the court should show more mercy to him than to a Hitler or Saddam who killed people for the same reason.