My phone wont seem to play the video. What are the important aspects revealed, besides difficulty selection?
Difficulty ranges from 1-10, Level 10 looks about to be quite difficult and stealth is a necessity. Around difficulty level 5 or so, enemies no longer show up as blips on the radar, so you'll have to go by sight and sound.
At the beginning, you select a random character, which does just that, gives you a random civilian at the start. By completing certain challenges, you unlock Heroes, ranging from Eli Wilkerson to Sam Hoffman and Sergeant Tan. Other Heroes span the range of cops, hunters, soldiers, a mercenary and a Hazmat suit-clad Hero named Degrasse.
You then pick a home base with other survivors and then it's good ol' scavenging and sneaking for supplies. With later difficulty levels, there's a more emphasized drain on your resources.