Is there any good retro 2d game engine assets around

Is there any good retro 2d game engine assets around?
when I ask this I mean support and editors for things like
retro tilesets
retro unit scaling and camera scripts
retro palettes
retro shaders
retro movement and physics
retro item and powerups
retro ai and pathing
retro multiplayer
retro intros and scenes
retro text and text scenes

if so can you link them
if not how much would it cost to pay someone to make something like this?

 

Hi
Feel free to check out our 2D assets:
https://www.assetstore.unity3d.com/en/#!/search/page=1/sortby=popularity/query=publisher:15526

We also do contract work

Here is some examples of our work

• 
  
  ________________________________________________________________________________________________
  2D Jungle Pack - Handcrafted Art
  Link!
  
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  2D Under water Pack - Handcrafted Art
  Link!
  
  ________________________________________________________________________________________________
  2D Graveyard Pack - Handcrafted Art
  Link!
  

 

Lots of free prototyping assets of all genres:

http://opengameart.org/