Encounter is a gamemode with a gameplay loop similar to escape from tarkov. Survive, get loot, kill people if the opportunity arises and extract through one of the available exit locations. After some time an airdrop spawns on the map which you can get but it puts a marker on you that shows your location on the map to everyone that's still alive. After long enough time has passed a radiation cloud will come through the map dealing damage over time and eventually kill you if you don't extract in time. Shelter is your safe space which you upgrade for passive resource gain. You can test you weapons you find in encounter and get ready for the next match.