Number 5: To The Rescue!

Honestly, this mission isn't as purely difficult as the next entries, but its sheer tedium can seriously push the limits of your patience. The 4 Black Lasers and Adder's frequent movement boosting CO Powers necessitate constantly checking all possible enemy attack ranges. Even one little misplacement can result in significant damage to your Bombers, which is ruinous for attempting to take out the Lasers.

I don't even know why they toss up the option for HQ capture as a victory condition, considering it's in the corner of the map and is heavily guarded by units. You'd have to be extremely daring or stupid to try capturing Adder's HQ. Finally, the super slow animations of the Lasers firing gets old quickly. I'm not sure if they fire faster in the reboot.

Number 4: T-Minus 15

The most difficult part of this mission is keeping your foot soldiers at full HP. If they are even slightly damaged, one more turn of capturing the cities can mean the difference between victory or defeat. It doesn't help that Flak, despite his general awfulness as a CO, can greatly screw over the situation with his wild Luck based damage.

The time requirement is also rather tight, further stressed by Flak's massive starting forces.

Number 3: Sea of Hope

A very difficult mission overall. Even if its time limit is not as strict as the previous entry, it more than makes up for that with the ferocity of enemy units. The assortment of Battleships, Rockets, Neotanks, and even Bombers can make the early portion of this map brutal. Sami's here to offer some covering fire, but there is a realistic possibility of her troops getting routed, resulting in a defeat somehow.

The difficulty is partially remedied by most of the Yellow Comet COs being pretty strong for this map (besides Sonja).

Number 2: POW Rescue (Hard Campaign)

For appearing so early in the Hard Campaign (Orange Star), this mission feels like a punch in the face in terms of difficulty. Fog of War plus enemy indirect units are a nasty combination, especially given the AI's notorious ability to ignore the mechanic of Vision (at least in the original). The Minicannons along the way also prove to be annoying, if not threatening.

As a veteran player, I can appreciate the challenge of this mission, but it's quite mind boggling how the difficulty of this mission is comparable to even the tail end of the Campaign.

Number 1: Danger x9

Holy crap, this mission combines the most difficult parts of every previous one on this list all into one little soul-crushing package. Super strict time limit? Yep. Difficult to capture HQ (Lab in this case). Uh huh. Fog of War? OH YEAH!

If you don't know what you're doing on a turn by turn basis, Danger x9 can push your skills to the absolute limit. The Green Earth COs, with the exception of Eagle, are just not that good in this game. There really didn't need to be any more additions to the "making things more difficult" department, but okay.

Hawke is a tough enemy CO for most missions, but his CO Powers which deal global damage can prove especially disastrous on this mission if it prevents you from scoring crucial kills. The base on the right side also serves mostly to troll you; building anything there only lures Hawke's entire army there, resulting in a slugfest that you likely cannot win within the time limit.

This mission is one that even experienced players can easily fail. Admittedly, this does make it feel so satisfying when you S rank it.