What are some alternatives?
When comparing Hollow Knight and Downwell, you can also consider the following products
Super Meat Boy - Let's start with what's the same: Dr. Fetus is still a jerk, gameplay is super challenging but fair, there are tight controls and great levels and you will die. a lot.
Braid - Resource planning & scheduling for professional services
Super Phantom Cat - Retro-inspired 2D homage to 8 and 16 bit platform games.
SuperTux - SuperTux is a classic 2D jump'n run sidescroller game in a style similar to the original Super...
Minilens - Libre puzzle platformer for gravity-oblivious aliens
Secret Maryo Chronicles - Secret Maryo Chronicles is an Open Source two-dimensional platform game and is using an Open Graphics Library for the best possible graphic design and stock performance.