[2] The duo's work, largely influenced by media and electronic music from the 1970s, incorporates vintage synthesiser tones, samples, analog equipment, and hip hop-inspired beats.

It has been described by critics as exploring themes related to nostalgia,[5][6] as well as childhood memory, science, environmental concerns and esoteric subjects.

They experimented with recording techniques from around the age of 10, using tape machines to layer cut-up samples of found sounds over compositions of their own.

It was described by Sandison as "a record for some sort of trial-by-fire, a claustrophobic, twisting journey that takes you into some pretty dark experiences before you reach the open air again.

Critics noted a shift in mood within Geogaddi; Mark Richardson of Pitchfork commented that "the atmosphere on this album is a shade darker than on previous releases, and comparatively tense with a noticeable thread of paranoia.

When writing about the album for The Observer, Simon Reynolds noted that "blurring the boundaries between rock and techno is a smart move, because BoC have always made music that deserved to appeal beyond the electronic audience", and praised "the stereophonic delirium of their production.

[31] Other codes were hidden through various websites and online communities, as well as being broadcast over BBC Radio One, NPR, and Adult Swim.

"[43] Critic Simon Reynolds described their style as "a hazy sound of smeared synth-tones and analog-decayed production, carried by patient, sleepwalking beats, and aching with nostalgia" while crediting them with "reinvent[ing]" elements of psychedelia through the deliberate misuse of technology.

[7] Their distinctive style is a product of their use of analogue equipment, mix of electronic and conventional instrumentation, use of distorted samples, and their layering and blending of these elements.

[44][45] To achieve their evocative and "worn down" sound, the duo have made use of outdated brands of recording equipment, such as tape machines manufactured by Grundig.

[46] They also make use of samples from 1970s television shows and other media prevalent in the era of the brothers' shared childhood, especially the nature-inspired documentaries produced by the National Film Board of Canada.

"[47] Interviews with the Sandison brothers have variously provided insight into their creative process: they have cited several acts that have influenced their work including Joni Mitchell, the Incredible String Band (saying "we have all the String Band records […] our rural sensibilities are similar"), the Beatles (saying "[they] really became enthralling to us through their psychedelism") and My Bloody Valentine (saying "even if we don't sound like them, there's a connection in terms of the approach to music").

[50] Brief interludes or vignettes feature prominently in the duo's music, often lasting less than two minutes; Sandison has said that "we write far more of [these] than the so-called 'full-on' tracks, and, in a way, they are our own favourites".

[51] When questioned about their aims in making such references, Boards of Canada have expressed themselves in neutral terms (saying "We're not religious at all [...] and if we're spiritual at all it's purely in the sense of caring about art and inspiring people with ideas.