"[3] Lopatin explained the imagined scenario behind the album's opening track "Nil Admirari": "the mom's sucked into CNN, freaking out about Code Orange terrorist shit, while the kid is in the other room playing Halo 3, inside that weird Mars environment, killing some James Cameron–type predator.

[1] Resident Advisor noted that the album begins in "comic assault mode—the crude tangles of noise, serrated drum machines and vocal screams of 'Nil Admirari'.

"[4] Sherburne described "Nil Admirari" as an "unexpected invocation" of noise music, employing "weeping voice, feedback squeal, synthesizer drones, and overdriven drum blasts" that "combust like a rocket on its launch pad,"[5] while The Quietus characterized it as "sort of hurtful: sliced-up aural detritus with no enduring rhythm or melody.

[7][3] Reynolds described closing track "Preyouandi" as "a shatteringly alien terrain made largely out of glassy percussion sounds, densely clustered cascades fed through echo and delay.

"[3] Fact described the album's sound as "a psychedelia more earthbound than cosmic", calling it "music driven by an ecological rather than a narrative impulse, more interested in testing the limits of space rather than telling stories within it.

"[5] Comparing Returnal with Lopatin's previous works, Tiny Mix Tapes described the album as "not just a collection of tracks but an indivisible and cohesive whole, held in place this time not by grids and zones but by atmospheres and plumes.