Location from Undertale / Deltarune by Toby Fox
The horror section — a dark, dripping sub-basement where Alphys's worst experiments live and where the game stops being funny for exactly long enough to terrify you.
The True Lab is Undertale's horror sequence — a brief, intense descent into body horror and moral consequence hidden beneath Hotland. Accessible only during the True Pacifist route, it reveals what Alphys has been hiding: the Amalgamates, the determination experiments, the DT Extraction Machine, and the video tapes showing Chara and Asriel's final days. The encounters are genuinely frightening — Amalgamates appear in the dark, their distorted forms approaching with sounds that don't match any known monster. An unseen creature follows you through a hallway. The bathtub encounter... you just have to experience the bathtub encounter. But the True Lab's horror resolves into compassion. The Amalgamates can be befriended. Their families are grateful. Alphys finds the courage to be honest. The game uses horror not for shock but to earn its emotional payoff.
Dark green-tinted corridors, foggy and grimy, a stark contrast to Alphys's bright main lab above. Beds, sinks, fans, and Golden Flowers scattered through the rooms. The lighting is dim and inconsistent. VHS tapes and computer logs document increasingly desperate experiments. Something is dripping.
Also known as: The True Laboratory, Alphys's Secret Lab