Celeste [official site] is simple enough. It’s a platformer about climbing a mountain in which you can jump, air-dash to clear larger gaps, wall jump, and hold down right-trigger on the controller to cling to vertical surfaces until your stamina runs out. You leap between platforms, you avoid the spikes, and it’s all very pleasant.
That’s how it begins, anyway. By the time I reached its third area, the last included in the preview build I’ve been playing, I’m fleeing from mirror-world clones of myself that mimic my movements and destroy me on touch and navigating the world via blocks full of colourful stars. With each twist introduced as I climb its mountain, Celeste climbs higher in my estimation.