I'm not entirely convinced that "All of us are Dead" really needs to run to a second season, but at time of writing the logic appears to be that one has been commissioned, so I'll stick my review here, rather than on the overall show page.
After a science teacher experiments go wildly wrong, a Zombie virus is unleashed at a high school in the South Korean town of Hyosan. As the outbreak worsens, the town is quarantined but a small group of high school kids remain trapped in the school, unable to get to a rescue centre. They come to learn that there are variant viruses alongside the main strain, and though most of the infected change immediately, some can fight their new nature for much longer.
There is an awful lot of Zombie content in the entertainment world, hell, there is a lot of Korean Zombie content at the moment. "Kingdom" for me, sits pretty high at the top of that pile and if you only have room in your life for one, I'd say that the historical angle makes that the clear choice. This wasn't bad though, by any means,I'd just say that the ground has been covered before. Favouring more of a rabid, "28 Days Later" style Zombie, over a shambling hoard, what variety there is comes in the form of the variant strains - leading to several characters across the season becoming infected but maintaining their personalities. The series looks really good though, particularly as the devastation amps up towards the end.
I did find the show pretty bleak at times. There are occasional comic relief elements but mostly it's a procession of the sort of loss and sacrifice that zombie shows are known for and it's particularly hard hitting at times, as characters we are with for a long time are lost. There are occasional lapses in the shows internal logic that don't quite sit right. I'd also echo the recurring criticism that it's perhaps a bit too long. 12 episodes, some at more than an hour did, occasionally, make it feel like a chore to get though - and I'm not sure where a second season has to really go. That said, I'll probably be back.