It is a very different kind of complexity. Games are super complex in a very limited set of boundaries (the entirely virtual world of that single game) and have very rigid timing requirements, but usually the requirements to a "released" game don't change that much anymore. Enterprise apps usually implement stuff that seems simple (buy some item in a web shop), but gets complex due to a nearly boundless world which makes it necessary for them to interact with nearly every other system out there (which also changes all the time after release, just like the requirements to our app do). Thus the complexity of enterprise apps usually can be found in their interfaces to other systems (including humans) and in the way in which the app handles requirement changes over time, while the complexity of games is found in the simulation of their specific game world (including graphical representation of that world). It's like games are introverts while enterprise apps are extroverts.
If you want to explode the complexity of each of these "classes" of applications, just add the thing that makes the other class difficult to the requirement:
- A game that allows players in its world to interact tightly with an entirely different game world (like "really different", with entirely different rules and game play) which also evolves independently over time and on an uncontrollable schedule
- An Enterprise app that implements super complex processes with thousands of different moving parts, modeled out into extreme detail and without the possibility to resort to "this is handled organizationally"