X-COM games in order
There are 9 X-COM games on sale here, from X-COM: UFO Defense (1994) to XCOM: Chimera Squad (2020), in the order each first came out. It lists the games on sale now, not every game ever made. Only keys and codes their shop says work on a UK account set a price.
Each price counts the fees its shop's feed gives. Some shops add a fee for some ways to pay. Some pay us when you buy through these links, which never changes the order. How that works.
X-COM: UFO Defense1994 · Steam£0.512 shops
X-COM: Terror From the Deep1995 · Steam£0.692 shops
X-COM: Apocalypse1997 · Steam£0.732 shops
X-COM: Interceptor1998 · Steam£0.712 shops
X-COM: Enforcer2001 · Steam£0.602 shops
XCOM: Enemy Unknown2012 · Steam£0.792 shops
The Bureau XCOM Declassified2013 · Steam£1.153 shops
XCOM 22016 · Steam, Xbox, GOG£2.983 shops
XCOM: Chimera Squad2020 · Steam£1.693 shops