My bad. I thought you were referring to those Falcon ride moments in Reach. Though that moment in Serious Sam was basically to showcase the fact that you go the bullet-spewing minigun than anything else. But that's kind of the big difference between the Halo series and Serious Sam series. Serious Sam is more of a throwback to the 90s era of FPSs with all it's crazy and hilarious hijinks while Halo is in the line of recent modern shooters that tend to be more serious, realistic (to varying degrees mind you) and story-driven.
I'll give you that but still the point remains. Halo has allot of on rails moments. There's plenty of room for seemingly endless waves of grunts coming at you.
But there are several things I would like to point out, first in regards to the Invasion of Earth. Now I have do doubt that the fleet seen in First Strike was being assembled for Earth's invasion but that fleet didn't see Earth. Truthfully the Covenant, save for two exceptions didn't know that Earth had a human presence much less that it was humanity's homeworld. Why do you think Regret showed up in Halo 2 with only what fifteen warships if he knew that Earth was man's homeworld. Also the invasion of the Sol System was different from Reach due to several factors. A) the fleet Truth had intended for Earth was wiped out, weakening their overall forces. B) for much of the actual invasion, not Regret's unintended attack the Covenant was going through a civil war. They couldn't bring anyway near the strength of the Reach invasion to Earth. C) their goals for Earth were far, far different than Reach. They wanted the Ark, everything else was to stall the UNSC as they dug up the portal.
Now this is where I have the problem.
In one part you're going with the books being canon. But in others you're saying the game is canon. This isn't 40K where we can argue that we are learning the history when the fluff is rewritten it's because new evidence was uncovered that exposed the truth.
There's plenty of room in Halo to create a good back story. The fact remains bungie has no idea what they are doing.
Why introduce spartan III's into Halo reach when they could have used II's?
Why was nobel team the only spartan team on reach? Jorge is confirmed to be a spartan II, where are the other spartans? MC is shown in cryo on the autumn. why wasn't he fighting?
Bungie screwed up. They were to busy making a final game to make a solid plot.