✓ Like Crumbling, it's known for deep RPG systems, turn-based strategy and adventure storytelling
≠ Where it differs: brings puzzle design, horror tension and visual novel storytelling, while skipping action RPG combat
Undertale is an independent role-playing game developed by Toby Fox.
Once upon a time, there were two races on Earth: monsters and humans, but a war broke out between them and the latter won. Seven greatest mages sealed the monsters underground and left one entrance through a hole in the Ebott mountain. A lot of time passed since the war, but a human child accidentally falls down the mountain.
Where it drifts furthest from Crumbling: combat and visuals.
It predates Crumbling by 9 years, with what that implies technically.