The existing HTML/CSS/JavaScript program is from a previous challenge problem, "JavaScript Diffusion Limited Aggregation" (http://www.hpcuniversity.org/students/weeklyChallenge/105/).

The C version should use the X11 library to create the visualization of each time step. The user should be given the option to specify from the command line the stickiness, number of microseconds between time steps, random seed, and number of time steps to run. If these are not set, they should be given default values of 100, 100, time(NULL), and infinite, respectively.

Here is an example of a different program that uses C and X11, for reference:
http://www.shodor.org/petascale/materials/UPModules/infectiousDisease/