Does it count as incest if you make a kid with your clone?

Air tight.

Each time this scene starts playing.

Well, some machines were invented before they were first used. For example the steamboat was already designed and brought to Napoleon, who dismissed it as being fake and a waste of his time, so I guess that it wouldn't be as easy as that. Also, I believe that quite some of the usefull inventions we would bring would be dismissed as being unnecessary. Why make a steam powered train when there are roads and horses? Why invest in making better and more expensive armour when your currently used phalanx is already enough to win you every battle?

I think the only way of doing this kind of stuff is by winning the trust of your lord by showing him obvious and small improvements until he'll allow you to do everything you want and then go all out. However, history is quite violent, so pulling this stunt off seems even more tiresome than getting my current live on track, though it is fun thinking about it from time to time.

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You'll probably get killed for looking weird before you could say 'oogabooga friendly'.
And at the time civilisation evolved, you'll probably not find a lord that has the patience and/or the time/resources for you to show him what you mean.

You'll probably have to take on a respected job and show your potential for quite a while before you'll get the time to actually show them what you can do, only to be murdered to death by jealous/paranoid lord or die from some disease.

Give the Romans the designs for a Trebuchet and get fed to the lions for not speaking Latin.