Seeing everyone say they have problems is weird, cuz I downloaded this when it came out and have been having no problems playing and getting in matches. If it was pulled it probably wasn't for any networking reasons cuz it was working fine for me.
The basic concept is an interesting one, it's a fairly simple deathmatch multiplayer shooter except zombies also spawn that attack players. It's like deathmatch but you also get points for killing zombies. As far as I can tell there is only one map and one game mode. I would really like for there to be a coop horde mode where you just work together to fight zombies. Controls are left side to move, right side to aim, default is auto-shoot but you can change to virtual buttons.
The one problem it has though, is that it's very pay2win. The default gear and pistol is barely enough to take out zombies and most players I observed just getting killed by zombies before I could get to them. Meanwhile, anyone who got the more expensive armor and weapons are comparatively invincible, and the second shotgun is the best weapon in the game having massive range, 1 hit kills for zombies and players and a surprisingly fast reload. Although not that many people are playing, you can already see how the game would be ruined by just players who buy the best gear and dominate everyone else.