STALCRAFT is a game in the MMOFPS genre with Survival Horror elements set in the Stalker universe. It combines an open world, RPG and a dynamic shooter component.
An emission is a sudden and powerful release of excess energy from the center of the zone. Practically, this is a 5 minute world event which occurs every 2-4 hours and will kill any player character above ground (even if the player leaves the game). The emission is weakest in its first and last minute.
Players should immediately find a shelter nearby and stay inside. It is highly recommended that you at least mark out the shelters in the area you plan to be in using a tool like https://en.stalcraftmap.net STALCRAFT map so that you can be ready in case of an emission. Note that you have exactly 1 minute before taking exponentially increasing damage. With enough health regeneration, you should be able to leave shelter in the last 1 minute of the emission.
It is always a good idea to know when the next emission might occur so that you are ready. This tool should help you get an idea as to when the next emission might occur. It can also save you from logging into an emission.