When comparing OpenGameArt vs Clickstore, the Slant community recommends OpenGameArt for most people. In the question“What are the best sources of royalty free game assets?” OpenGameArt is ranked 3rd while Clickstore is ranked 18th. The most important reason people chose OpenGameArt is:
All assets made available through OpenGameArt must be licensed under one (or more) of the following: CC0, [OGA-BY](http://opengameart.org/content/oga-by-30-faq), CC-BY, CC-BY-SA, GPL or LGPL.
Ranked in these QuestionsQuestion Ranking
Pros

Pro Committed to free/open licensing
All assets made available through OpenGameArt must be licensed under one (or more) of the following: CC0, OGA-BY, CC-BY, CC-BY-SA, GPL or LGPL.
Pro 2D and 3D art
OpenGameArt has both 2D and 3D art assets.
Pro Big library of varied CC0 assets
OGA currently has an impressive library of free assets, especially in the texture department.

Pro Supports asset requests
OpenGameArt has community forum sections dedicated to Resource Requests and Open Commissions.
Pro Lots of free items
Pro Open Source Game Templates
Pro Effects Libraries
Cons

Con Mediocre organization and search functionality
The curator of OpenGameArt acknowledges that the tools for finding the assets you need are sub-par. Correcting this is a near-future priority for improvement, and as of September 2014 is the next milestone goal of the site's Patreon campaign.

Con Assets may have restrictive licenses
OpenGameArt hosts art under any of several licenses, some of which may not be suitable for commercial projects or for release on certain distribution platforms. Careful review of which licenses are compatible with your project is essential. The site's search facility allows filtering by license.
