25 years after its release, Valve’s classic FPS “Half-Life” received an anniversary update. However, after the commemorative update, V released a new patch that solved a bug that has plagued the game for decades. The bug appears in the famous scene in Chapter 6 of the game: a tentacle breaks through the glass, knocks a scientist to the ground, and drags him out of the room. Under the influence of BUG, players can see that the animations of alien tentacles and scientists are out of sync.
Original screen:
On social media, Valve programmer Ben Burbank explained the reason for the new patch. He said that Valve originally hoped to fix this bug in the 25th anniversary update, but "the release of other things has higher priority."
He went on to explain: "This is not a systematic error and seems to be largely limited to this one scene. Mainly because it's the only scene that relies on synchronizing multiple animations, and there's a section in the middle where the actors need to find their way around space before the animation plays."
Valve has three options: try to fix the code, change the animation played, or change the map to normalize the playback time. Valve finally chose the third option. "If we fixed the sequence so that the scientist's timing was correct, the player could still stand in the doorway and shoot the scientist, interrupting the sequence, and then he would animate in a weird way," Burbank said. "So we wanted to change the way the sequence was triggered so that it didn't interrupt."
"However, recompiling the maps will produce a large number of changes in the resulting binary space partitions (remember, these maps were last compiled on a Windows 95/98 machine). Any bsp differences may lead to small but annoying path and conflict bugs. We don't want those."
"So we ended up just doing a hex edit of the map. Triggering the animation when the door opens (some community mods use a decompiled or recompiled version of the map to trigger the animation, rather than the moment the player walks through the door, ensures that the player can't shoot the scientist before the animation starts syncing."
Danny O’Dwyer, director and editor of the Half-Life: 25th Anniversary Documentary, provided some additional background information on the bug. When Half-Life was released in 1998, the animations seemed to line up as expected, but post-release updates resulted in bugs. He told IGN that "the animators were in sync when the game was released, but something happened over the years that caused them to no longer be in sync," but it was unclear exactly when the bug first appeared.