*Brofist.
Dat ODST vibe. Plus dat backdrop. The first time in the game you realise you are actually fucked.
See, that should have been obvious from the get go, not eight missions in. I forget who did it (pretty sure if was a GAFer), but somebody put together a new intro for Reach that made it very clear you were fucked before your boots every touched the ground. They also cut out Winter Contingency, if I remember correctly.
In my mind, I expected Reach to open like Aliens (and the rain-soaked search for survivors certainly helps); a small squad goes in on a routine mission and all hell breaks loose. From the second you see Covenant on Reach, it should be non-stop chaos and destruction. WC went on too long and levels like Nightfall (which felt tacked on, almost like "we need to add a T&R-esque sniper/canyon mission in because that's what everyone expects") threw off the pacing. The game took too long showing you Reach was under attack when we all knew (or should have known) from the second we started how bad things were gonna get.
I don't have time to sit and rework the story, but even keeping that intact there's things that could have been done to kick players in the teeth right away;
Keep Winter Contingency, but make it about half as long. When you first start, you've spotted the troopers' dropship, crashed into the Relay structure, and drop behind a farm to give you a safe approach (so you can still have that bit of dialogue with the farmers). When you clear the farm and reach the relay, you step into the aftermath of a battle; wreckage and bodies everywhere, but no hints at who or what caused it. Because the dropship crashed into the relay, you assume that's why there's no communication. The wreckage has also blocked the front door of the structure, so Kat directs you to an outlying maintenance building that connects to the Relay via tunnels. Once you get down there, it's all interiors and a few small courtyards for the rest of the level and the Covenant comes on quick and strong, dropping in from above.
Remember that Halsey's friend was working on some kind of Forerunner info, so the Relay interior could be expanded to house a secret ONI data processing center. You'd get through the usual communications equipment, round a corner, and find yourself in lab with clean rooms, huge super-cooled rooms filled with computer, a huge, super-cooled room with mainframes. Not only does this give you a reason and an excuse to have a larger interior, but it makes it a little more apparent why the Covenant strike team was there (to get the Forerunner data) and why they attack it so heavily afterwords; the datapad you find contains all the information, which would have been wiped from the mainframes as soon as they saw Covenant forces. And they obviously want it back.
When you finally get to the Relay control room (I picture it looking like a Flight Control tower), Carter says something like "Kat, we need the relay up, we need to inform Holland
now", Jorge or Emile points out the window and says "I think he already knows, sir" and you see just a shitload of Covenant Corvettes dropping out of orbit and they're already laying waste to shit.
Basically, put emphasis on the interior of the relay instead of a half-dozen rinky-dink farms. I know they were trying to build up tension, but that was pointless from the start because we already knew what was coming. I know Halo is also all about large outdoor areas, but there would have been plenty of that to come (and remember, Halo CE started with the PoA interior to make getting around easier).
Meh, just my two cents.