Events

Events are a feature in, similar to the Daily Missions from the mobile port of. Their inclusion in SAS 4 was announced on a Ninja Kiwi blog on September 5th, 2014. They can either be passive events, like Spitter Bounty, which tracks how many Spitters the player kills in Multiplayer matches, or Matches themselves, like Alpha Virus. The more a player completes the requirements for an Event, the higher their rank gets on the leaderboard. Once the Event is up, they will be rewarded based on their placement on the leaderboard (if they at least reached the Bronze Rank). Being in the top 75% gives a Bronze Rank, 50% a Silver Rank, 25% a Gold Rank, 10% a Platinum Rank, and finally 1% a Diamond Rank.

Spitter Bounty
Spitter Bounty is a passive event. The focus is to kill Spitters in Multiplayer matches.

Alpha Virus
Alpha Virus is a match the player has to directly participate in. They will have the 'Alpha Virus', and will move slower while their health degenerates; additionally, zombies will be more attracted to them.