Samurai Gunn is great. It's a mainstay in my living room, especially with the backwards compatible PS1 taking a dive (no more convenient Bushido Blade). I also gave it a 2014 game of the year award even though it came out in 2013 (I also did this for a game that came out in 2006, because fuck it).
Developer Beau Blyth has been busy on Hyper Light Drifter, but he's still tinkering with Samurai Gunn in his leisure time. First, it's coming to Mac tomorrow, January 29.
Everything that's been added to the Mac version is coming to the PC version as a free update. There's 10 new levels and 2 new modes. Master of the House cycles you through a random stage in each of the four areas, while Showdown Shogun lets you just play no bullet showdown stages. There's also a new, moonlit showdown that's quite pretty.
There are other technical and polish additions. Widescreen support, better controller connectivity, updated visual effects, toggle for team killing and lives per match, and the ability to replace blood spurts with cherry blossoms, which sounds beautiful.