OK - I really am getting close to the first alpha release (I wish I had a buck for every time say that). Just tidying up the example mini games and other minor tweaks (perfectionism can be so debilitating).
What you will get in the alpha (in no particular order)
A GPU based physics engine that may or may not work on your graphics card
Save and load worlds (or selected particles as assets).
play with gravity strength and direction
create new element/particle types
set and display the world objective (fledgling game development)
select a language - thanks Google (probably all gobbly gook for non English speakers)
a short getting started guide
undo/redo (forward/rewind/single step) of simulation
two type of pause modes (normal and matrix - aka bullet time)
multiple particle layers
individual layer editing
select by particle/particle type/rigid body
copy and paste particles
move particles directly or via a force
weld / break / join / delete and change particles
pin particles to the background
draw particles freehand / line / square / rectangle / circle / oval
spray particles
follow an individual particle
world zoom
disintegrate / explode / freeze and melt particles
change simulation frame rate / speed
play with world viscosity and density
set world ambient temperature / lighting
heat / cool particles and have them react through temperature changes
wrap world horizontally and/or vertically
independently change the horizontal/vertical size of the world
visualize particle forces
display engine stats and individual particle velocity and forces
give each particle type a name and description
change particle mass / impulse / restitution / repulsion and friction
add a life force to particles
define reactions between particles based on impact / tensile forces and temperature
reactions can annihilate / transmute or create new particles
change body rigidity (both tensile and flexibility)
add control inputs to particle reactions via keyboard / mouse (controller coming soon)
combine existing particle types to create new particles
assign particles to a group
apply short and long range forces between particles
live coding of force equations (using glsl compute shaders)
live coding of particle reactions
live coding of particle and light geometry / fragment shaders
apply thrust / impulse / torque / drag and brake controls to particles
assign sounds to particle reactions and collisions
use particle properties to vary sound by volume and pitch
frame rate tests for 16k, 32k and 64k particles
big bang mini game
frubbles mini game
car on a rope mini game
bottle flip mini game
fireworks