Current State of the PC version (as of 2pm 04/14/15):
• Single Fight (I've tested versus CPU, but not 2 player)
• Practice Mode
• Fatality Practice Mode
• Most option menus (Control Pad menu crashes the game)
• 23 of the 25 characters (Shinnok and Goro require you to finish story mode before they are available)
• Story Mode
• Sub Zero
• Literally everything else not listed under "Working"
Let me know if I missed anything, or if anything has been fixed since I last checked.