When I upgraded to XNA 4.0 my particle system broke because point sprites were no longer supported. Shawn Hargreaves explains why they were removed in this article. I added the particle system early on when I didn’t really have the look and feel of my game well defined. It was something I had already created in another project so it was easy to port over. Explosions consisted of a bunch of points with random directions and velocities emerging from a single origin.
With the upgrade to XNA 4.0, it forced me to not only rewrite parts of the system, but also gave me a chance to update the look of the explosions to match with my current game aesthetics. Here are the new explosions in game:
My goal with the explosions was to create the impression that the blocks were exploding into a bunch of visible pixel blocks. I replaced the points with quads of varying sizes and colours. I also added collision detection with particles against blocks. The particles reflect their direction vector based on the surface normal when a collision occurs, but there is still some wonky behavior during puzzle rotation collisions that I may work out later on. Anyways, I’m pretty happy with the end result.