To celebrate its 25th birthday, Valve updated Half-Life and gave it away for free. At the same time, it released an hour-long documentary in which the original developers talked about making the influential FPS. In the documentary, Valve's co-founder Gabe Newell explained why game delays are OK, but also took some time to explain the theory of fun Valve came up with while developing the original Half-Life.
"We knew it was an ad hoc definition," Newell said, "and it was the degrees to which the game recognizes and responded to the players' choices and actions, right? In behavioral science, you would say we were explicitly talking about what were reinforcers and what the reinforcement schedules were. Right? At that point in time, that was a useful way of making design decisions."
Some of those design decisions, Newell went on to say, were ensuring the marines ran away when you were winning, and having bullet hole decals appear in walls when you shoot them. The last one seems to have been particularly important to Newell, who describes their absence by saying, "it feels like the wall is ignoring me. I'm getting a narcissistic injury when the world is ignoring me."
Knowing they'd need to have a melee weapon, they settled on one that could easily smash crates and made a satisfying clang when it hit a wall. "It really goes back to that theory of fun," Newell said. "We were just running around like idiots smacking the wall. It's an odd thing to know in retrospect, but at the time it felt profoundly satisfying to be able to smack walls. And that was just an example of how that fairly abstract notion of what fun was ended up translating into a set of decisions that were really visceral. When you're going around whacking a wall, a crowbar is an obvious thing to whack the wall with "