So on halo reach I had trouble unlocking a few achievements:
-
Tank beats everything - I completed the mission on legendary, barely taking any damage. I did however see a video saying that you have to practically drive into the bunker so i’ll give that a go when i’m ready to face it again. (also could i take it from a later checkpoint or would I have to start the mission from start?)
-
Defiant (although i have unlocked some ages ago)
and
- anniversary
simple as.
do these have to be completed on the designated map packs as I have completed both the infection achievements exactly (on infection not alpha zombies)
and if so, what kinda chance does that give me to earn the achievements?
- You need to take the tank all the way to Sword Base and you need to be driving it to my knowledge.
2 & 3. The following achievements, although have the Defiant label, do NOT have to be unlocked on Defiant maps:
Return to Sender
Crackin’ Skulls
Candy from a Baby
The rest which are as follows:
Don’t Touch That!
Paper Beats Rock
All Alone
do have to be unlocked on a Defiant map.
All the achievements that have ‘Anniversary’ on them have to be unlocked on any of the maps from the Anniversary map pack, whether it is the Reach counterpart or classic variant designed for Anniversary settings.
> 1. You need to take the tank all the way to Sword Base and you need to be driving it to my knowledge.
>
> 2 & 3. The following achievements, although have the Defiant label, do NOT have to be unlocked on Defiant maps:
>
> Return to Sender
> Crackin’ Skulls
> Candy from a Baby
>
> The rest which are as follows:
>
> Don’t Touch That!
> Paper Beats Rock
> All Alone
>
> do have to be unlocked on a Defiant map.
>
> All the achievements that have ‘Anniversary’ on them have to be unlocked on any of the maps from the Anniversary map pack, whether it is the Reach counterpart or classic variant designed for Anniversary settings.
Thanks for the info. too bad there’s no dlc playlist anymore… 
Also I did the tank one single player 
Tank Beats Everything - Finish the 9th mission on Legendary with the scorpion intact.
The achievement pops after you pass a certain checkpoint whilst in the tank. You do not need to play the entire mission for this achievement. The checkpoint is located in the area just before you are forced to get out of the tank to continue with the mission. you must be in the tank at this checkpoint to earn the achievement, if you are not in the tank, you will get nothing, even if the tank is in perfect condition.
Defiant and Anniversary Achievements
I think you need to do these achievements on the designated map packs. I tried doing the “From Hell’s Heart” achievement on the Rumble Pit playlist but it didn’t work. Then I did it on the Anniversary playlist and it worked. I also tried doing “Bounty Hunter” on sword base, but that didn’t work.
It’s a pain that you need to do these achievements on the map packs because you never get an infection game on the anniversary playlist. It’s also rare to find a game with everyone having the defiant map pack. I’m in the same situation as you are
If you ask me, it gives you a low chance to earn the achievements because of the rarity of finding the game type you need for the achievement, such as infection and headhunter.
I hope this helps.
For what it’s worth I did Tank Beats Everything ages ago, not long after launch, no problem. I seem to recall jumping out at the base once the checkpoint tripped so maybe that’s it…
…however, some months later, and through several attempts, helping a friend get it acting as wing man while he drove the tank we completed it but it never unlocked for him. Has me wondering if the achievement is broken in some way from a TU, the more so now if you’re having a hard time getting it.