Extra (Edit): After going through lots of free resources, I’ve created the SpriteWorld web page. It’s a collection of some the many free resources I’ve found.
Feel free to browse through and don’t forget to +1 if you like it. 

 
Although Sprite Would has a lot of content, I still recommend you read thought this post.
 
Another highly recommended reading for developers is this awesome post.
 
— Original Post below —

 Metal Slug cloning

 
– Some nice Metal Slug-like character animations. 
 
 
 
 
 
 
 

 Lost Garden 

.. a great site with lots of links to free stuff, more below:

 
– Really nice looking 🙂
 
 
 
 
 
 
 
 
Small World (Lost Gardens)
 
 
 
 
 
 
 
 
 
Zelda like (Lost Gardens)
 
 
 
 
 
 
 
 
 
 

 hasgraphics.com 

contains a very nice list of free sprites:

 
Disclaimer from hasgraphics.com:

All the sprites found on this site are free to use for commercial and non-commercial projects. All the sprites are the property of their respective authors and Has Graphics only features them. We carefully inspect all the sprites we publish to make sure they fit certain quality criteria, and most important that they are available for non-commercial and commercial game projects.

 
 
 
 

 SpriteLib

 
Also a nice list, although I find the tiles very small.
 
If you would like to show your appreciation for SpriteLib, please consider making a small donation. 
All donations are handled securely through PayPal and do not require an account.


 
 
 
License: Unkown
 
Attached File  Slope_1.gtx   
Attached File  Slope_2.gtx  
 
 
 
 
GfxLib-Fuzed is a package of free art assets which can be used by game developers, hobbyists and enthusiasts for their own projects. It is available under terms of the Common Public License .
 
 
 
 
 
 
 
 
 
 
 

 http://opengameart.org/

 
This website is great and has so much quality tiles that I recommend you to have a look by yourself. 

Collected Art: 
Preview
Note: Overall the website seems to have a lot of contents, however after a brief search I found very little  free CC content. The stars rating is reflecting my opinion as a website for free resources for indie games, not as a whole.



Some other findings:
 
Aparently DeviantArt has lots of isometric view tilesets: http://browse.deviantart.com/digitalart/pixelart/scenes/iso/
 
 
other,
http://fav.me/do00wz
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
I liked the website, however didn’t really find easy to use tiles.
 
 
The best resources sites I’ve found so far.
However I’m not sure regarding the usability of the contents… looking briefly to the forum it seems that it’s good for play, not good if you want to make money (otherwise I would give it 5 stars):
 
So basically, you can use sprites as long you never receive a single cent for whatever you do with them. (This includes “voluntary donations” which is a popular excuse used by smug people whi think they can fool the law with semantics.)  (link)
 
 

 engine001

Lots and lots of resources, however files are in a strange format and tilesets seem too simple.
 

Unrated:

http://www.gsarchives.net/
http://www.bghq.com/
http://acidsound.blogspot.de/2012/02/spritetitle-resources.html
http://www.freewebs.com/dlbrooks33/dlbrooks33.htm

 

Forums:
http://www.sprites-inc.co.uk/forum/ (very promising)

http://www.spriters-resource.com/community/

 

http://z15.invisionfree.com/DJ_Universe/index.php?showtopic=2645

Extras:


Here are some sound and music links:

http://www.wildbunny.co.uk/blog/2011/12/11/how-to-make-a-2d-platform-game-part-1/

Sound effects asset resources
Page name/link    File formats     Details    Active   User can contribute   Licenses   
Freepats .pat   Instrument patches for software synthesizers Yes Yes CC0, GFDL, GPL, LGPL
Freesound .wav, .aif, .flac, .ogg   Community-based sound library Yes Yes CC0, CC-BYv3
Obiwannabe sounds andgenerators .mp3, .pd   Various game dev sounds including procedural generators for such No No CC-BYv3, GPL[4]
OLPC Sound Samples .wav   Instrument and music samples, sound effects Yes No CC-BYv3
OpenGameArt sounds flac, mp3, ogg, wav   User-submitted repository of game sounds Yes Yes CC0, CC-BYv3, CC-BY-SAv3, GPLv2, GPLv3
public domain sounds .flac, .ogg   Sounds mostly in mp3 format Yes Yes CC0


https://love2d.org/wiki/Free_Game_Resources

 is an online sound generator.

 (Swedish)

 (Requires registration for downloads, but otherwise bullshit-free)

 (might be down, check out this in that case)

 (make sure you learn the license, it is not exactly CC)

 contains free songs and loops.

 another listing-type page. Licenses vary.

Music:

 (Various)

 (Evil chiptunes. Big plus for umlaut. Licensed CC-NC-ND. Use with caution.)

 (Chiptunes) (Licensed CC-NC-SA. Use with caution.)

  • Creative Commons’ own list of music, containing lots of links. Two examples below:

 is a “a community music site featuring remixes licensed under Creative Commons where you can listen to, sample, mash-up, or interact with music in whatever way you want.”

 is a “100% free AIFF/WAV collection contains 6.4 GB of sounds”

 


Also, let me know if you know a good site for me to add.


 

Keywords:
128×128, 16×16, 2d, 32×32, 64×64, 8 way, character, game, isometric, MM7, platform, platformer, RPG, sprite sheet, sprites, tileset, 32 bit