Nobody is saying that porn 'makes you' do or become anything. But the stories told in video games are clearly fiction in form and content - you're a soldier in the future fighting aliens, you're a member of an elite group of time-traveling assassin's, you're an aspiring ex-convic with unlimited lives and pockets to carry an entire arsenal of weapons in a tanktop and shorts - whereas porn is written to make the fantasy seem just plausible enough so you can place yourself in as the subject (which is why the situations are always so contrived in pornography)

The situations wherein you might plausibly choose to sexually exploit a child aren't nearly as implausible as one where you could violently assault someone without immediate risk and consequence. Just look at how often porn dialogue waves away the likely objections; "we're not actual siblings, you're just my STEP brother", "I won't tell anybody", "I just turned 18, I don't want to be the only virgin in college", ect.