Volcanic Ash is a scenario. It is similar to Pirate Plague, except that it doesn't affect boats. In this scenario, there are a lot less planes than in normal gameplay due to an increase in volcanic eruption, resulting in dangerous air conditions. This makes the Air 1 and 2 abilities less useful, requiring a change in strategy.
As taken from the Scenarios menu:
Massive volumes of volcanic ash are ejected into the atmosphere from major volcanic eruptions. The majority of flights worldwide are grounded, changing the way that people travel. Does this cloud have a silver lining?
- Using Spore Bursts, the player can get their Fungus over to other countries without having to wait for boats.
- C. America is a great place to start, as you will rely more on boats. In addition to this, this country has a very popular Seaport.
- The Special Plagues are mostly unaffected by this, allowing for more flexible strategy planning.
- Unlike Pirate Plague, travel to Greenland is not inhibited by this scenario at all due to the fact that the elusive island country only has a seaport.