Joe Wintergreen is an Australian indie game developer who is currently working on “mostly a stealth FPS” under the Impromptu Games banner. He also recently delivered unto the internet a series of code snippets from the great FPS Half-Life 2 by way of his Twitter account. There's not much to see of the code, but that's not why we're here. What's really relevant are the code comments, and the light they shine on how the magic is made.

The first tweet in Wintergreen's thread sets the tone for what's to come:

Good to know Valve and I pretty much have the same comments in our AI pic.twitter.com/TrWO8KUAadSeptember 1, 2016

Striders will intentionally shoot things up even if you're not in their line of sight, just because it looks cool:

Strider might still shoot if it knows it won't hit ya if there's something there it'd be cool to hit pic.twitter.com/fHwWO7Cw6CSeptember 1, 2016

Charlie don't surf, and the Combine don't dance:

A fix to make combine soldiers not dance. pic.twitter.com/aXDrhAUk5gSeptember 1, 2016

Zombies had to be toughened up after the shotgun's power was increased, to keep things in balance:

Cool little comment about rebalancing zombies after some changes to the shotgun happened. pic.twitter.com/XxM3ntFm4vSeptember 1, 2016

This is a stupid fix but it works, so whatever:

Might as well continue this thread since I found another good HL2 comment. Feel validated, everyone! pic.twitter.com/gYBCZJJvaRSeptember 2, 2016

There's only one “fuck” in the entire codebase, according to Wintergreen, and this is it:

Respect to Valve for having only one "fuck" in the entire HL2 codebase. pic.twitter.com/zKNF4ygjIvSeptember 2, 2016

Alyx Vance: Nice girl, handy in a fight, terrible eyesight:

Ah, good bit of HL2 Ep1 commenting (kind of thing they'd put in the dev commentary). On Alyx/barnacles in the dark pic.twitter.com/DhYyooJOyGSeptember 2, 2016

Some of comments really give a sense of what goes into making a game and keeping it intact. One in particular is actually a multi-paragraph telling of how the Strider minigun was accidentally nerfed in the Orange Box because of a bug in the original Half-Life 2 that nobody noticed. There's also a bit about the “low violence” mode, and references to the Combine Advisors, “large sluglike aliens with creepy psychic powers” who ended up not being used in the game. [Correction, sort of: I've been reminded that they did appear in Half-Life 2: Episode 2, but you didn't actually fight them.]

It's a fun bit of videogame history, and there are quite a few more than just what's embedded here. If you've got a few minutes, you can catch the entire thread on Twitter.