So you mean this neon-effect?

Well the purpose of bloom is: Bright parts bleed over dark parts.
And that's exactly what my shader does an what's beeing done in the screenshots you've posted (except the 1st one, I think this are simple 2d textures).

Let's take the last screen as example. ( love that game btw. )
To get that effect simply use sprites and add a bloom shader with very low threshold.
That's all.
You probably need 3 Bloom passes to get that radius with a good quality but in theory that's all you have to do.

edit: as you can see it's possible (and easy)

I took the bloom shader and turned down the threshold.
( and I discovered that using pow on the alpha causes early bleeding which is perfect for a neon-effect )