Yeah I had a look at that, modular upgradable weapon system, it seems like a cool idea. But how can you test it without a game engine to run it in? Are you doing this for fun/learning or do you have a market you plan to sell it to?
I will eventually develop a complete FPS game engine. But, for now, I can settle with droping a controllable camera in a empty level map; mounting GunVertor and firing away. As far as making money, the game engine will be a freely available workhorse for developing TournamentBlitz Service enabled FPS games.