Cave Story+[Mac, PC, Linux] [DRM Free]

Arguably the most well-known indie game of all time, Cave Story features a completely original storyline wrapped with personality, mystery and hours of fast-paced fun. Cave Story is an action-adventure game from the critically acclaimed independent designer, Daisuke Amaya--or Pixel to his fans.
Source: http://store.steampowered.com/app/200900/

This version is the one from the Humble Indie Bundle. It works on both OS X, Windows and Linux. DRM free version so no need to crack

Enjoy and seed!