24/20 Hard Mode (6850 Points) Re-Beat | UCN: Recode 

It was where at 1am, 3am, 5am a plushie makes a noise and you need to remember what order of sequence it was because at 5:59.9 you will need to buy the plushies in the sequence that it played in or else you die right at the end if you failed :))

Exactly what kingpin said but they also spawn normally without a sound cue from what seems to be every 35-48 seconds I would say