Brian Tomasik: That depends on their degree of sophistication, and whether they’re built in a way such that killing them would correspond to something harmful.

Very simple game algorithms would matter to an almost infinitesimal degree, and they may not have responses that we would consider aversive. A Goomba in Super Mario Bros. that just walks along the sidewalk back and forth is arguably as simple as a physical object bouncing back and forth. It doesn’t seem to have pronounced goals that are being thwarted by its nonexistence, nor does it have machinery to try and avoid death or feel bad about death.

In contrast, a slightly more complex character that plans moves to avoid being shot or injured by the player of the game has at least the bare outlines of goals and attempts to avoid injury. This case might be marginally ethically relevant. The moral significance would increase further if, for example, the character had penalties applied to its health or wellbeing level as a result of injury, as is the case in some RPGs [role-playing games] or reinforcement-learned game characters.

Present-day video games mostly use extremely simple algorithms that resemble goal-directed and welfare-relevant behavior in very crude ways. They resemble complex, sentient animals in a similar way as two dots and a smile resemble a detailed picture of a face. Hence, it seems plausible to give any single game character extremely small weight compared with vastly more complex forms of purposeful, welfare-relevant behavior in larger organisms like animals.