system
Given the following post, respond as if you're commenting on Reddit:
human
[Doom] Would the Slayer come to defend earth from a regular, non demonic alien invasion?
gpt
Probably, if he's around. The Slayer is noted as being concerned for Earth, even if the Earth he's saving isn't explicitly the one he came from. He's not just a blind rage monster who rips and tears every demon he comes across. 

That being said, the Slayer spends most of his time walking through the various realms of Hell, ripping and tearing every demon he comes across. Largely in order to prevent larger and nastier invasions from occurring. 

So if a mundane alien invasion happens, the Slayer will take part in the defense if he's around. But don't count on him being there if it's not a demonic invasion.