This inspired the two to start a noise music project, but instead of guitars, they would use electronic sounds made with a circuit-bent Atari 5200–which effectively led to the media pigeonholing the act as chiptune, despite the fact that the members themselves didn't deliberately intend this.

Despite being labeled as the group's debut album, Crystal Castles is a compilation of singles that popularized the duo internationally, as well as unreleased demos recorded in 2004 along with two new songs: "Courtship Dating", and "Tell Me What to Swallow".

"[7] In analyzing how this relates the music that appears on their self-titled debut album, Edgar Smith of Time Out London wrote that the meaning of the tracks come from their "splintered melod[ies] and melancholic drum-loops" and not from their incomprehensible vocals and lyrics.

[7] Kath explained that in order for music to have "annoying" elements he created many of the sounds used on Crystal Castles by sampling textures produced from a circuit-bent Atari 5200 console.

[13] Ian Cohen, a contributor for Pitchfork, analyzed that while the content on Crystal Castles spans multiple genres and types of structures, "the body of the album can be distilled to an essence of the glassy, ten-lane stare of Last Exit with Ed Banger's egg-frying EQ".

[10] Tiny Mix Tapes writer Cor Limey labeled the LP as "independent" from similar nostalgia-driven indie electronic music because of its elements of irony and self-awareness.

[6][8] Journalist John Brainlove categorized it as a "hit and run electropop" song that includes "flailing, pulsing beeps smashed over an evil beat and driven onward by an incomprehensible shrieked vocal".

[9] Cohen labeled "Good Time" a "veritable toybox with undulating octaves, an almost Eastern-sounding riff and tweaked nice-guy vocals which combine the Knife and New Order".

[28] Some critics praised the LP's unpredictable nature;[14][19] AllMusic journalist Heather Phares described the album as "fresher, more complex, and much less gimmicky than might be expected, especially for those familiar with only the band's singles" and a "familiar-sounding, edgy, innocent, menacing, bold, nuanced, and altogether striking debut".

[21] Tony Naylor, writing for NME, noted feeling "intrigued and awestruck" after listening to the record and opined that "you will hear nothing better this year than" the tracks "Untrust Us", "Crimewave", "Air War", and "Vanished".

[27] A critic for Prefix called Crystal Castles "an electro record that challenges, succeeding and failing all at once, and perhaps most important, never forgetting the primary goal of dance music".

[15] A reviewer for Drowned in Sound stated that "what makes Crystal Castles so thrilling is that [the duo] turn the fruits of [the availability of technology] into weapons to use against it, using [it] to cut through the shitty mire".

[18] He praised it as "a crystal castle of technological rubbish fusing together under the harsh gaze of a falling sun, Kath and Glass digging around in the molten plastic for things to bang together, new-age Stigs dreaming of leisure's lost golden age in a data dump".

[29] Dorian Lynskey of The Guardian summarized that the record is "all manic with youthful enthusiasm but unsatisfyingly feels half-finished, as if Crystal Castles are still struggling to mould these wonderful sounds into something coherent".

[11] In a piece for The Skinny, Sean McNamara opined that most of the album's content was "static, ZX Spectrum computer style melodies and sheer noise-a-rama", which was disappointing given that songs like "Crimewave", "Magic Spells", and "1991" show "real evidence that when they calm down a bit they can produce some high quality electro that is a delight to hear".

[30] In Dave Hughes' review of Crystal Castles for Slant Magazine, he noted three types of songs on the record that he marked as "Wii", "Xbox", and "Huffing Paint Thinner".

[12] "Wii" tracks, which include "1991" and "Black Panther", are "stupid, simplistic, and incredibly fun" and have "ping-ponging keyboard melodies and stray laser beam noises" foreground in the mix with vocals that work as "atmospheric background mumbles".