This is an example of a program that has been written by a group of students adapting the tutorials that I gave them at the start of the semester, which in turn were based on the 2D tutorials on the XNA Creators Club site.

XNA student program

The cannon that was fixed in the bottom left hand corner of the screen can be moved freely around.  In addition, although it is hard to see on the image above, the enemy UFOs drop bombs.  The explosion effect is pretty impressive and utilizes some nifty particle code.

XNA program: space invaders

Another group of students has created a great Space Invaders clone.  The enemy space ships do speed up quite a lot towards the end and the frequency of their bombs increases – which makes it quite challenging!