Tuxmath contains a game activity called "Factoroids", which is a factoring game inspired by the arcade classic "Asteroids."

Currently, the target numbers on the rocks are randomly generated.  One idea that might make the game more educational is to have each wave add one more prime factor.  In other words, the first wave would be all powers of 2.  The next wave would be numbers that are multiples of twos and threes (e.g. 2, 3, 4, 6, 8, 9, 12, etc.).  The third wave would be multiples of 2, 3, and 5.  This could be continued up through 13 or 17, perhaps.

The code that controls this behavior is in factoroids.c

This task will involve setting up a working build environment on your computer, then modifying the C code in factoroids.c to change how the numbers on the rocks are generated.  You should not need to mess with autotools or cmake, except to execute the standard build commands.

The completed project would optimally be submitted as a diff between the final and original source trees.  As this is all within one file, the final factoroids.c could be submitted as a simple file attachment.

(this should be significantly easier than the task to create a server selection interface.  In both cases, much of the work is just a matter of getting a working build environment set up, which is pretty easy in Linux but really painful in Windows).