Left Behind

How, when and why unused code sticks around.

- Xalavier Nelson Jr.

Every other day, it seems that some band of intrepid dataminers finds hidden, outdated, or mysterious content buried in the code of our favourite games. This isn’t negligence. Instead, it’s a peek into a little known reality of game development: that unused code is left in databases because it’s too risky to remove.

Defender’s Quest DX dev Lars Doucet compares disabled (rather than removed) code to a nest of cords. “You can’t say for certain what is plugged in to what without taking a lot of time to figure it out.” This is especially true if you didn’t write the code, for instance if you’re working on a large team. Deleting old, seemingly obsolete code can risk breaking something important.

Industry veteran Tom Forsyth explains how keeping disabled code around allowed Oculus to release Positional Time Warp (tech that smooths perceived motion by tracking depth information and movement) in 2018. “For various non-technical reasons, the feature was removed,” Forsyth says. “[Fast] forward to more than THREE YEARS later, and in 2018 Oculus announce this new feature called… Positional Time Warp! And it’s exactly the same as the thing it was before. … If it hadn’t stayed alive in the (very fluid) codebase all those years, it would have been a huge pain in the arse to reinstate, and probably wouldn’t have got the go-ahead.”