I don't know much about Untiy but I know how effects like that are produced. They take randomly generate particles around the area, I'd guess they used Perlin Noise. And in each update, if the particle is no longer visible, it's deleted to make more room for new particles. This should produce the effect you are looking for.

Here is a few links on Perlin Noise: http://webstaff.itn.liu.se/~stegu/TNM022-2005/perlinnoiselinks/perlin-noise-math-faq.html http://freespace.virgin.net/hugo.elias/models/m_perlin.htm http://en.wikipedia.org/wiki/Perlin_noise https://www.google.com/search?hl=en&gs_rn=12&gs_ri=psy-ab&tok=LdTwrXJiymKnamCUgCaPaA&cp=10&gs_id=1c&xhr=t&q=perlin+noise&bav=on.2,or.r_cp.r_qf.&bvm=bv.46340616,d.cGE&biw=1920&bih=979&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=BVOPUfzLFuHsigLGlYGwCg

I also recommend taking a look into Simplex Noise. Pretty much a newer version of Perlin Noise.

I don't know much about Untiy but I know how effects like that are produced. They take randomly generate particles around the area, I'd guess they used Perlin Noise. And in each update, if the particle is no longer visible, it's deleted to make more room for new particles. This should produce the effect you are looking for.

Here are a few links on Perlin Noise:

• The Perlin noise math FAQ
• Perlin Noise
• http://en.wikipedia.org/wiki/Perlin_noise
• Perlin Noise images

I also recommend taking a look into Simplex Noise. Pretty much a newer version of Perlin Noise.