As part of the game I am creating an "Event Deck" to enhance game play
In the initiative deck I have two cards: one allows for an event if drawn before the turn ends, and the other kills off the chance for an event if drawn before the other card.
This can make the occurrence of an event possible, but not so frequent that it controls the game.
An event can change the way the game is played and adds the "Murphy" factor. Some events are good - like finding some ammo or food. Maybe a friendly survivor comes to the character's help for the remainder of the game.
Other events can hinder the characters and really throw a spanner into the works.
Another kind of event is a 'plot' event - something that drives the story behind the campaign.
I prefer an event deck to a chart, as you can re-arrange the deck with a minimum of effort and cater it to what figures or scenery (if needed for the event) rather than roll on a chart and find you don't have a figure needed, or that the result rolled on the chart totally blows.
You can also include more than one card of a particular event to increase the likely hood of an event happening, or not happening as the case may be.
I make the cards like I do the initiative deck cards - print a front and reverse side and them laminate them to protect them from excessive handling.
So far I have 80 event cards, with more to be added as I go along. I don't use all the cards at once. Instead I select a certain variety of cards to suit the scenario.
The type of cards I have are:
Bonuses - anything that helps the survivors with dice rolls
Penalties - anything the doesn't help the survivors with dice rolls
Items - an item that can be used during the game or essential supplies
Rumors - used to drive the plot: who caused the apocalypse, news of safe havens
Encounters - good or bad guys that turn up during a game: Government Agents, Corporate Soldiers, other Survivors, Bikers, SEAL Teams, Delta Force, Military - both local or foreign.
Story - a card that develops the story and drives the campaign a certain way.