Mindclash is 'introducing' Voidfall as a space 4X game. What's a 4X game?
It is designed by Nigel Buckle (Imperium: Legends/Classics) and David Turczi (Anachrony) with illustration and graphic design by Ian O'Toole (On Mars).
Image Source: Mindclash Games
4X means eXplore, eXploit, eXpand, eXterminate.
Then I might be wrong but I understand the four keywords that way:
eXplore means you don't know the whole map at the beginning, you reveal bit by bit (hex by hex in the old school video game titles).
eXploit ties to resource management: you can extract resources from the territories you discover/own, can build buildings to improve this extraction, etc.
eXpand means you can improve your civilization/faction by researching technologies with long-lasting effects.
eXterminate entails combat. Simple one. A fight-free, peaceful 4X is in fact a 3X.