What ZS Online is
ZS Online is a top-down 2D shooter set in a big city, and a single round runs about 10 to 16 minutes. You scavenge materials during the day, combine them into knives, guns, throwing tools, armor and food, and try to be the last player standing. Buildings are full of materials to pick up, and you can also harvest trees and fruit. Hunger ticks down as you play, and moving faster drains it faster. When hunger hits zero your stamina drops, so eating food is the way to get it back.
How your group plays it
Everyone drops into the same large city and plays against each other as the match goes on. The map tracks other players' positions during the day, but stepping inside a house hides your marker from them, so buildings are where you can lose someone or set up an ambush. Fights are direct PvP: whatever you crafted is what you bring. When only one player is left on the map, that player wins.
Day, night, and the gas
Daylight is for looting and crafting. At night the view narrows, zombies come out, and other players disappear from the map, so it becomes a fight against the dark as much as against each other. Every day the number and variety of zombies grows, and poisonous gas starts hitting the city. Planning your route around the day/night cycle matters more than raw aim.
Before you start
You pick a character with different abilities before a round, so your choice shapes how you play. Zombies, the shrinking safe space from the gas, and rival players all pressure you at once, and a round is short enough that a bad start costs you little. The game can be played solo without an internet connection too, with a different ruleset: zombies appear during the day and in greater numbers, and no poison gas hits the city, so you score points instead of being forced into the same endgame.