From the Steam Sale, some casual games about playing with the odds:
Peglin is quite fun and short. The more pegs you hit, the more it damages an enemy. Highly replayable with all the modifiers making each game unique.
Roll is similar, modifying dice to get the highest score in 2500 rolls. There is way more complex calculations, but I like how messy it gets.
From the ones already on the library, just Hollow Knight which has been a delightful yet frustrating experience. The soundtrack is stunning, and I love me some platforming challenge.