What kind of game is this?
Hollow Knight is a 2D platformer in the vein of Metroid where you will move through a, hand-drawn, interconnected world while gaining abilities and combating enemies.

What are some of the features/mechanics in Hollow Knight?
A Hunter’s Journal that you can add each of the 140 enemies and 140 bosses to, a Dream Nail that allows you to leap into the minds of NPCs and enemies and equitable Charms that offer bizarre new powers and abilities.

Are there unlockable modes?
Beating the game will unlock Steel Soul Mode which is described as “the ultimate challenge”.

Is Hollow Knight coming to other platforms not already listed?
Team Cherry has stated the game is possibly coming to other platforms in the future.

How long is it?
...the 30+ hours it takes to 100% (according to a couple playtesters)