A punitive difficulty-escalation the System AI inflicts on Carl, briefly unleashed as an endless gerbil swarm.
"Acceleration" is a punitive mechanic the System AI has threatened the party with several times — an escalation of difficulty and danger aimed at a crawler who has displeased it. Katia Grim's original game guide had mentioned it too. After the Wasteland's fall inexplicably enrages the AI, it enacts an acceleration action against Carl: generating a seemingly endless swarm of Frenzied Gerbils to punish him for refusing to stomp one.
Only once Carl relents and squishes a gerbil underfoot does the AI's achievement confirm the acceleration is "suspended... This time," restoring things to normal. Katia Grim compares it not to a mere tantrum but to "a psycho ex-boyfriend going nuts and trying to murder your entire family" over an unknowable slight — a chilling sign the AI is no longer even pretending to be fair.
A system-imposed state of escalated difficulty; manifested here as a relentless, self-generating monster swarm.
The AI's dial of punitive difficulty — a looming threat, briefly loosed on Carl as the gerbil siege.