State Changes

When you heat up water, it turns into a gas (steam); when you freeze it, it turns into a solid (ice). Similarly, gases can condense and solids can melt. These are state changes. Do you want them in your virtual world?

A virtual world can be satisfyingly convincing without state changes. If you don’t have any way to heat up things or cool them down, explorers might figure out why and get uppity but most of the population will take it in their stride.

On the other hand, state changes aren’t all that hard to implement and can impress the players. It can be done quite easily as a destruction/creation pair: Destroy the steam, create the water; destroy the lava, create the rock. In real life, state transitions take energy to effect (it’s how refrigerators work), but in virtual worlds where people don’t have accurate thermometers, there’s no need to worry about it.