I just did Legendary today. That’s every Halo for me, except Wars and Anniversary. I only did reach less than a week ago, I’m on a roll. If you get stuck on any bits tell me and I’ll tell you how I did it. I am not that great compared to many people on this forum. But I can just about do it with enough determination and planning and recon for health packs and ammo. I needed a lot, but there are a ridiculous amount of them in the game even on legendary. Especially health, even I didn’t use 65% of the health-packs.
The streets sections are not the toughest parts of this game anyway. Play it in order, you’ll get more satisfaction from it. There was one very hard bit on Mombassa streets, the final time you go there. I had no decent weapons or ammo. And there is a Chief Brute with a (1-hit-kill) Fuel-rod launcher surrounded by another Chief Brute with a Carbine and several other brutes protecting a jackel with a sniper-rifle. What a nightmare! I picked them off one by one and wandered around the level until I jammed a savepoint and then went back for more. Over and over, till there were just the 2 Brute Chieftains. I found a Mongoose and 1-hit-kill splattered the launcher one, which I wasn’t even sure was possible, but it is. I was airborne and full speed and hit him smack in the face. And then, it’s just you and 1 brute chieftan in a one-on-one. But you have a launcher
That was the worst bit in the game for me actually, no ammo or long-distance weapons I could find.
Also remember on some levels you have an invincible team-mate who you can swap weapons with. They never ever run out of ammo. If there is a really hard bit, give him a shotgun or even better sniper or rockets. And just watch them kick -Yoink-. This is also crucial on the Warthog levels. If you can get a side-passenger with a sniper-rifle. It really is so useful, but obviously you will have to find one for him. A weapon only need 1 bullet left to give to a helper, they can use it forever.
On the shortcut, you may make it harder for yourself. I could be wrong, but i’m sure some of the missions in the streets get you weapons, from the hidden caches or otherwise, that you can take through into other levels if you play it in order. I really needed that Mongoose, without it and it’s 1-hit-kill splatter ability I would have taken many more deaths. I’m sure that Mongoose was there because I parked it there earlier in the game. Again I could be mistaken, the game overlaps and winds around so much.
Also the easiest way to complete these Halo games on Legndary is always “Kill everything”. Total Covenant ethnic-cleansing, dodging and ducking makes you die more if like myself you’re not that epic a gamer. I always take them out in order of weakest first, grunts, then jackels, then Brutes. It’s less covering-fire for their side, a grunt is as good at hurting you as a brute until you take it on.