Edit: As pointed out in the comments, this was originally a visual novel! There are many ways to enjoy this story.
Stiens;Gate is the only time traveller story that I know that establishes rules for time travel early on and actually sticks to these rules till the end.
There's also Primer, but Stein's gate is better than that movie.
Personally I find this much more refreshing than the usual the-world-will-collapse scenarios. It's easily one of my favorite films, just because of how different it is than it's ilk, I've yet to find something like it again.
Using time travel as a plot device versus using time travel to explore part of our humanity is a mark of great science fiction.
In particular, what's up with that hangar full of troops and equipment at the "end"?
The other one (Abe) stayed back and kept on trying to travel to the past and messing around with the machine so that his (and Aaron's) past selves will eventually give up assuming that the machine doesn't work. But this seems to have been thwarted by one of the future-Aaron's as he has sent a recording detailing the whole scenario to some unknown recipient (this recording serves as the narration of the movie).
No, you can only go back to the point where you start the time machine. Secondly, its Aaron, so its probably his private corporation running the new machine. Aaron is the one who is manipulating the stock market and in it for the profit.
Its the "success" story for Aaron, he rebuilds a bigger time machine, but with the power of a corporation / large money backing him now (probably funded from repeatedly winning in the stock market). Aaron cannot stop the original experiment or otherwise travel to the past, but he can make money in the future.
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There are roughly 3 machines you need to be aware of.
1. Machine #1 is what the movie is mostly about.
2. Partway through the movie, Machine#2 (failsafe) is revealed. The main character turned on the failsafe simultaneously with Machine #1, so if the time-travel got too confusing, he could always go back to the beginning and turn off Machine #1, cancelling the entire experiment.
3. The other main character, reset Machine #2. Instead of sending you back to the beginning, it now sends you to Day2 or so, preventing the change of the early days.
4. The conclusion, where Machine #3 is revealed. There was no leadup to machine#3, its just a bit of closure for the greedy Aaron.
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The movie goes off the rails and really stops making sense. I've put a lot of effort into trying to understand what they were going for... and ultimately came to the conclusion that Stein;s Gate is just a better thought out time travel plot.
I give Primer credit for being a relatively consistent time-travel movie with more thought put into it than the average time-travel timeline. But the ending is still in the "audience's hands", and still leaves ambiguity for the audience to figure out on their own.
A lot of actions in the middle of the movie don't seem to have any relevance to other events. The father (Thomas Granger) randomly coming in through the time machine but unconscious for example. While it is clear that Thomas Granger is from "some future timeline", such an interpretation naturally conflicts with the Primer theory thus far (which has no "multiple timeline", everything should be consistent)
There is also an Aaron clone running around, but it isn't really clear from what time the time-clone is from.
A lot of people are tricked by the crystal clear beginning and assume that the end makes sense, but the movie goes into ambiguous mode about half-way through. Its audience interpretation, as opposed to a singular answer. (Contrast with something like Inception, which doesn't really have more than one interpretation).
Some people like ambiguous movies. I don't, which is why I kind of prefer Stein's Gate, where all actions are clear.
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Either way, its clear that the powerful organization is Aaron's goons. Aaron was the guy who played the stock market with the time machine, so its obvious that Aaron used the time-machine for ill-gotten gains at that point... and is using the money to fund a bigger time machine.
[0]: https://en.wikipedia.org/wiki/The_Man_Who_Folded_Himself
IMHO, Steins;Gate hasn't clarified what time travel really represents. When one travels from one world line to another, does the previous world line still exist? Is time travel a travel between parallel universes, a complete rewrite of history in the _same_ world, or something else?
In the first Steins;Gate anime, it seems that time travel means a rewrite of history (i.e. the conventional type of time travel in science fictions), but in Steins;Gate 0, time travel seems more like jumping between parallel universes.
Aside from that, it wasn't a great show (only 1 series made) and watching the first episode[1] back I can safely say it's not aged well either.
But it's one show that has always stuck in my memory for when the writers actually took the theory of time travel seriously.
Either the sub or the dub is well worth watching, but the dub is one of my favorites. In particular, it shines with Okarin's mile-a-minute pseudo-scientific conspiracy rants.
If you like the premise and the characters, but are frustrated at the slow pace, hang in there. The plot does eventually kick into gear, and it doesn't waste any of the character development or world building.
https://polsy.org.uk/stuff/ytrestrict.cgi?ytid=https%3A%2F%2...
I'd suggest going with the visual novel anyways, since it has a bit more meat (like multiple endings) even if the anime is a pretty faithful telling. It's also on so many different platforms (including iOS), so it's pretty accessible.
I'd avoid Steins;Gate Elite like a plague though.
It's not _bad_, but I don't see any reason to go with it over the original.
PS3 and Vita was years later (2012)