The Moon and Eggmanland: Double Case Study

The Moon

Many have speculated about what the break-up of the Moon in SA2 would have done for the planet Sonic lives on. While I previously theorized why we can't see the crater in later games, I haven't touched upon that subject yet. In order to actually figure out what it would do to the planet, we would first have to figure what it would do to the Moon itself. And so, assuming the SA2 Moon has the same physical and orbital properties as our own, I went ahead and calculated some of the Moon's characteristics after the break-up. Very roughly, I admit, but we're talking planetary scales here, so a few million or even billion tons off doesn't have too big of an influence. If you want to check my calculations, you're welcome to: The Moon: Calculations
If you don't and you just want the results, read on.

I used this picture as a reference:
 

Diameter of the crater: ± 3000 km.
New mass of the Moon: ± 5.84 * 10^19 metric tons (currently 7.3 * 10^19 metric tons, so approx. 80% of its current mass)
New volume of the Moon: ± 1.8 * 10^10 km³ (currently 2.2 * 10^10 km³, so approx. 82% of its current volume)
New orbital velocity: ± 0.84 km/s (currently 1.022 km/s, so approx. 82% of its current velocity)
New mean orbital radius: ± 438,000 km (currently 384,000 km, so approx. 14% wider)
New orbital period: ± 33.2 days (currently 27.3 days, so approx. 22% longer)

And here's the big thing: what would this do to Sonic's world? Well, it clearly wouldn't result in a moon as big as it was in Hang Castle or the intro to Shadow the Hedgehog, since the Moon is farther away. This also means no more total eclipses like in Riders, as the Moon is now too far away to fully cover the Sun, seen from Earth. And the tides get less pronounced as well, since the Moon's attraction on the world's oceans is less strong. They wouldn't disappear completely, though, since the Sun is also a factor in the tides and the Moon is still in orbit. There's also a few long term effects, like the rotation of the Earth would no longer get slowed down by quite as much.

The biggest change blasting open the Moon would provoke, would be a semi-long term climate change. This is related to an Earhtly parameter called obliquity. Obliquity represents the change in tilt of the Earth's axis. Currently, it's in a 41,000 year cycle, wherein the Earth's axis tilts between extreme angles of 22,1° and 24,5°. The Moon is a major factor in upholding these boundaries, and if its attraction is lessened, these extremes will vary more. It's not as if the North Pole is going to move, the rotation won't be affected, but the angles at which it will face the Sun will. This means seasons will be more pronounced, and as such, climates become more extreme. But this will take more than a lifetime to have an effect.

So, no, as it turns out, blasting open the side of the Moon wouldn't really make a lot of difference over the course of the games. And as I previously theorized:
The SA2 Moon: A Case StudyDuring the events of Sonic Adventure 2, Dr. Eggman blows up half the moon (not exactly correct, more like a crater the size of Pluto) using the Eclipse Cannon on the ARK with 6 Emeralds. It is a matter of controversy that every portrayal of that moon since SA2 has shown no crater. And there have been many. Moon Zone in Advance, Hang Castle in Heroes, the opening of Shadow, the ending of '06, a cutscene in Terminal Velocity in Colors, and I must have missed several. So what's with that? In real life, the answer is most likely rendering issues, but is there a reason in-game?
Takashi Iizuka (involved with many of the games from 3&K up to Generations) has confirmed that the reason is the most logical explanation that no one seems to think of, namely that we're only seeing the face that wasn't blasted open. But then comes the question, why is it turned? Aside from reasons giving Sonic or Eggman or anyone else credit for it, there is a natural explanation to this. I won't discuss the eff 
Since the Moon would turn its whole face towards Earth, we would be quite unaffected. The night sky would be a little less bright and the tides would fluctuate less. That's about it, in the timespan we're talking in the games.

Eggmanland

We all know how Sonic Unleashed ended for Eggman. With Dark Gaia betraying him and Orbot (or SA-55 as he was called back then) insulting him on his failures. But if you look closely, that doesn't really hold up. In fact, Eggmanland as whole is quite anomalous. Let's take a look. 

The timeframe in which Unleashed takes place is actually not that hard to come by, because of the Day-Night gimmick, and we can be fairly sure that the entirety of the game takes places over two to three weeks. Now, anyone who's played either version of Unleashed knows that Eggmanland is obnoxiously huge. In the HD version, it's a level that takes 25 minutes if you're good and skip most of the fighting, and in the Wii version it takes a Day stage and five Werehog levels to get to the Gaia Temple. And I think we can assume that Eggman didn't have Eggmanland before he had Dark Gaia, as he credits Dark Gaia for its creation alongside himself. 

This would mean that the massive factory/theme park complex that is Eggmanland gets built over the course of those three weeks. I can hear you thinking, he has an army of robots, surely it's not inconceivable. But he has even less time to build it. If Dark Gaia's energy was crucial to creating Eggmanland, he wouldn't be able to do so until he had fused Dark Gaia back together, which doesn't happen until Sonic gets the Holoska continent, the fourth in the line-up, in place. Which means Eggman has a week, maybe 10 days to build Eggmanland. And I'm sorry, but it's just not possible to build something as big as Eggmanland in that little time, no matter how efficient your workforce is. And not only that, but that figure assumes that he's building in a place that was previously empty. What if he had to clear a city underneath it? This was his plan in SA1, mind you. 

Timing concerns aside, let's say he does manage to build Eggmanland in a week. You have Sonic, who comes in, makes it through, restores the final temple and is then dropped to the planet's core by the Egg Dragoon. There's a climactic battle, in which Eggman gets knocked away and Chip and Sonic fight and defeat Dark Gaia. Now, at what point is Eggmanland destroyed? The temple being teleported out would presumably cause some damage, yes, but it wouldn't destroy everything. The temples aren't that big, Sonic can clear the Gaia Colossus in 30 seconds. And even the continent's violent shifts wouldn't do much damage. The other cities survived the break-up and re-insertion just fine, and they weren't mechanical fortresses built entirely out of metal and concrete like Eggmanland. And Eggmanland, mind you, only had to make it through the re-insertion, as it didn't exist before the break-up. And even if Dark Gaia's power kept Eggmanland rolling, it's still there. Get Eggman to hook up some nuclear reactors (or Chaos Emeralds if he feels like it) and the place would be up and running. 

So, no, Orbot. Eggman's efforts weren't utterly wasted. Eggmanland exists now. It's a thing. It's still there. Maybe damaged and powerless, but it's still there. Eggman, whether you want it or not, you've achieved at least partial victory this time.