An enterprising (and dedicated) modder has replaced the sound effects in Half-Life 2 with ones that give the game a slightly more ... "human" touch.
Making sound effects for guns is something that humans have been doing since ... well, probably since guns were invented. "Pew pew pew!" That's either a laser, or a Hollywood Silenced pistol. "Cha-CHNK!" That'd be the reloading of a shotgun. "Bachabachabacha" is a machine gun, and so on. That's precisely what dedicated Source Engine modder Tr45e did, demonstrating his mastery in a YouTube video.
With the exception of some ambient sound effects and the voice acting, his mod (available here) will replace every sound effect in Half-Life 2 with one generated by his own voice - all in all, he ended up recording and replacing an impressive 1327 sound files in total. Weaponry, footsteps, vehicle noises - they're all man-made, and while it strikes me that this mod is something that could wear on you very, very easily, it's pretty amusing to watch. The first half of the video or so is just him demonstrating the various sound effects - skip to about 3:35 to see some gameplay.
I think my favorite part about this is just imagining Gordon Freeman fighting the Combine while making machinegun noises as he fires. I guess he's not such a silent protagonist after all.