I create this topic so as to show some screenshots of Game Develop, a free game development software, and more precisely the Particle system extension, based on SPARK :
Various effects :
Edition window of the "Particle emitter" object :
Game Develop is freely available on the official website. Examples displayed above are available in the example folder, under the name of ParticleVarious.gdg and ParticleExplosion.gdg.
As official extensions are free ( Free as in freedom, zlib/libpng licence ), the source code is available in Game Develop SDK : http://www.compilgames.net/code/GameDevelopSDK/SDK159954.7z ( Folder Extensions/ParticleSystem ).
Finally, I'd like to thank SPARK developers for their awesome work, concerning the library but also for the documentation and tutorials ! Thanks a lot !