If I was to go to WW2 and help the allies, I could tell them many of the battles in advance. I could tell them where they were going to attack. I could even tell them where their enemy leaders are at any given time. It is basically cheating with not only maphack but with foresight as well. I could give them 21st century computer technology, explain the principles behind nuclear bombs so that they could get them decades before the other side. Heck I could just go before WW2 and stop the whole thing from happening by shooting the future leaders with a gun before they were big shots.
And what we see today will never ever existed thanks to past modification.
Equally well I could join the other side and help them take over the world. Since I am from the future I know the weakest spots of all the other sides and what they know. Conquering UK? No problem just keep bombing London even though there is a weather warning for a storm that never happened and they will surrender. Russia? Just pretend to attack them, let them destroy their cities but instead retreat and keep bombing them if they come after, they will be so weak you could conquer them later. USA? Well thanks to my future technology just nuke Washington with a ICBM and GG.
Now that I like to see how one would do such thing, it's not a simple feat. It requires strategy and a base of operation. Also, we need to convince them to work that way so it makes things goes in our favor. Else it's nothing but hopeless, you might even loss your life in process.
Yeh this is why time travel is rigged. All you need to do is find someone who believes you and you literally take over the world as knowledge is power and you know it all. You choose what happens as your knowledge is ultimate. USA as part of UK? Warn about the rebellion in advance and have founding fathers executed. Germany rule over all Europe? During WW1 get them to not charge over the trenches like the British and instead work on developing nuclear weaponry instead (since you know it is possible and does work). Napoleon ruler of UK? No problem, learn French and tell him to not attack Welington at Waterloo and instead to set a trap. Julius Caesar supreme Emperor of Rome? Warn him of his assassination and let him do all the executing.
And yeah, then everything will be pretty much FAR beyond our comprehension.
Anyway, you're right, time travel is VERY rigged due to one coming from the future already knows what's in the past. So they can toy with it and alter it.
Only problem would be the middle ages where proving you are from the future is virtually impossible without them thinking you are a devil and burning you for being anti Christian. You would need to be more subtle and probably work your way into the Church to be immune to their accusations. All other times you could probably just brandish a modern phone or something and everyone would believe you.
As long as one's careful with your actions, one shouldn't provoke them in the first place. But if one do, if one can Time Travel, why not escape? If not, why don't one use one's Equipments and try to survive.
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A Plus, Dollar might never be an International Money Value Comparison if Time Travel did happened.
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Anyway, I'll choose either at year 1400/1500 or so when Europeans starts come to Indonesia and start their reign over us and stop them beforehand, so my country resources will not get sucked by them.
Then, afterwards I can show my children and grandchildren how awesome I was ^^
