Those that think they've seen it all and think they're "immune" or used to it make the dangerous mistake of sometimes searching for NSFL content that are sometimes mentionned on those types of questions just to test themselves.
I've seen a lot, way too much for my own good, it is never a good idea to search something like that up.
Truly hope your sibling as well as yourself aren't too scared of what it was you saw. Some of the content seen can sometime leave pretty heavy or permanent marks.
Can probably play Doom