I've been refreshing my memory of Upwards, Lonely Robot [official site] via the game's free Steam demo. It tells the tale of a robotic ball who climbs towers while guzzling fruit and avoiding mechanical insect enemies.
The specifics of the story are unclear to me at the present time as the demo only has 5 levels available to play, but the in-demo text offers "a touching love story to tell your grandchildren" and 75 levels of story.
You can also check in on the customisation menus for the climber challenge levels (where you can set your own difficulty by playing with a bunch of settings like spikes, enemy types, tower size...), the infinite mode and the multiplayer bits where you can race with friends by creating or joining servers without actually being able to play any of those - they're more just teasers for things to do in the main game.
I actually played Upwards, Lonely Robot at the RPS unofficial fan convention "The PC Gamer Weekender" earlier this year. I played maybe a dozen levels(??) and although it got trickier mechanically it didn't feel like it got more varied so I my interest started to flag simply because the levels started to feel samey. It wasn't bad, though and I liked how the robo-ball moved, my mind just started to wander. You can set harder difficulties in the main game so perhaps that would help. You can't go above normal difficulty in the demo though so I can't tell.
Also, a word to the wise: the game was set up at a booth with really tall stools and I felt really unsteady on mine so the constant need to orbit the tower as I climbed gave me really bad vertigo and I nearly fell over. Only a little bit - like, I needed to catch onto the desk to steady myself and felt a bit motion sick. I didn't get it when I was playing the demo and sitting somewhere more secure but it's maybe something to be aware of if you get disoriented easily when playing?