The reason that the three of us (it was actually 5 in the beginning but we tragically lost two along the way) choose to do a game on the HL2 engine is because of several reasons. One, all of us were familiar (not to say experts) with the HL engine and, two, it would allow the team to shine with our graphics work, which is what we are all good at. Three, we all love FPS games and this was a chance for us to actually work on the back end (for a grade, no less) and see how the games are put together. Fourth, although this does just apply to the webmaster, I want to work in the video game industry when I get out of school and this is an excellent learning opportunity for me.