New Super Mario Bros. 2

• Levels use SARC files. RoadrunnerWMC's NSMB2 editor and Every File Explorer are able to unpack them. WiiUExplorer/related source code/SARCUnpack might be able to unpack them, but not in the current state.
  
• Ninjifox has made a proof-of-concept version of Reggie! Mod that can view NSMB2 levels. It is not going to be released! But he has done something that somebody could also do, even if he is not making the stuff public. Screenshots: Skawo's, Ninjifox's.
  
• There are some BCTEX textures.
  
• Messages use MSBT. They can be read in a hex editor.
  
• Models use BCRES which has a CGFX in the header. It may be a 3DS version of the Wii's BRRES or a CGFX file (you don't say). CGFX files can be opened in 3DSExplorer, converted to obj with cgfx2obj and viewed with Every File Explorer.
  
• Music streams are BCSTM can be played/converted with foobar + vgmstream or just converted with vgmstream. But the 'gold' sound cannot be disabled, as of a while ago.
  
• Entrance usage
  
• NSMB2 can be repacked.
  
• http://pastie.org/pastes/10534949/text?key=0mjgmwbz1drkkltq3irg
  
• Lighting is based on the bg
  

1. Hacks

• Super Mario Bros. Next - Halloween Special by Next Team
  

2. Info

• List of Files
  
• List of Sprites
  
• Differences and similarities to other games
  
• List of Actors
  
• List of Tiles
  
• List of Unused things
  
• Early Lists
  
• List of Versions
  
• List of File Formats
  
• Gold Ring Behaviours
  
• Sprite usage (includes main game + dlc, nybbles 1-24)
  

3. Workings

• a
  

4. Ideas

• a
  

5. Reggie! Files

• music.txt
  
• levelnames.xml
  
• spritedata
  
• Sprite Images
  

6. Tools

• Reggie! Next
  
• cgfx2obj
  
• 3DSExplorer
  
• Every File Explorer
  
• Coinkiller