I don't know if this has been posted here before and I think I've read somewhere that there's gonna be a particle emitter on the next version... but here's a really simple particle system... I was playing with particle on my game and it led to this.
It consists of 2 actors: emitter and particle. I also added in a text input so that you can see a change while in-game.
Red: particle type (currently 0 and 1 type only)
Green: number of particles
Blue: gravity(you can type in negative sign but it wont show though. I have no idea why.)
http://www.mediafire.com/?q0c6ph2s0m3ewtu
hope this will be helpful...