Just played this for the first time, joined by 2 friends as a co-op Ironman run on Classic difficulty. Let me tell you a little story about a man named Humberto.
Born in a small town in Argentina, Humberto Castillo had the build of a linebacker, and a heart of gold. The lone survivor of first contact with the aliens, he went on to become a Heavy operative, and the star of the X-Com program. When X-Com shot down their first UFO, he lead the charge on the ground. When terror struck the streets of Germany, he held his team together long enough to get the job done. When the council needed a VIP extracted from a ravaged city, and when everyone who deployed with him was dead or dying, Humberto stood his ground, squared off against 4 Sectoids and 2 Thin Men, and won, carrying critically wounded Squaddie Flores back to safety. Though wounded on countless missions, Humberto "The Man" never asked for medical attention in the field, always saving it for the rookies. When he wasn't recovering from grievous wounds that would have killed a lesser man, Humberto deployed on every mission throughout the lifetime of the X-Com project.
Months after first contact, with satellites being shot down, Asia falling to Chrysalids, and humanity rapidly losing ground, things were looking grim. The X-Com project was suffering in both funding and manpower, and had resorted to selling their cutting-edge technology and alien salvage just to bring in enough fresh recruits to fight. Only a few parts of South America, Africa, and Europe remained outside a state of mass hysteria. Every other veteran operative on the X-Com project, from the most elite sniper to the greenest medic, had died as the cities of the world fell... all but Humberto.
It was there, in the ruined streets of his beloved Argentina, that Humberto lead humanity's final stand against the aliens. His squad were pinned down in a warehouse by Floaters, who were firing on anyone who emerged from the building. With two of his rookies already gunned down, he ran out into a parking lot in a desperate move, and against impossible odds cleared the skies long enough to let the rookies escape the warehouse, and make a break for the transport. Over-exposed, 3 hulking Mutons charged across the parking lot at Humberto, but rather than retreat with his rookies he met them in battle. Sustaining heavy fire, he still managed to fire his single-shot rocket launcher to demolish a car, and the Muton hiding behind it. A few rounds of concentrated LMG fire took out the second, but it was a lucky shot from the third Muton that finally ended Humberto's life, and with it the X-Com project.
Though what remained of humanity's legacy was crumbling down around them, those three rookies Humberto gave his life to save held their ground against the invasion... and held it to the very last. It's what Humberto would have done.