I've been playing a game of catching up with unit testing and features. But after having written unit tests for XML, geometry optimizer, particle manager, and various minor tools, I feel much more confident about the code base as a whole. There are more components to be tested, such as Physics and Scene tools. They are still need to be refactored a bit to remove inter-dependencies. Mm... still need to think about this.
However, I'm not writing only unit tests at this point, I'll still pushing forward with getting second demo done. Nothing major needs to be implemented at this point. There are a few minor and annoying things to be dealt with. Things like incorrect aiming when the tank tower is not horizontal, or hitting your own tank when launching a missile from the gun.
A few mode models, a little bit more exciting level design, and second demo will be rolled out. :)