Hey! Thanks for the kind words, we worked very hard on this game so its nice to hear some feedback. Sorry about the mac support, we will tackle that some day.
As for your questions:
- there are 16 levels
- there is a boss at the end of each of the three zones, there are also some mini-bosses along the way
- As for the upgrade system, you have 16 different skills you can choose from, but you can only have 4 skills equipped at once. There is also a talent system with 20 different talents that you can put points into. Overall we feel that there is a good amount of build diversity. In our play testing we were able to come up with some pretty crazy builds.
-we started working on the game in October of 2010. You can actually find some of our old posts on this forum while we were trying to figure out how to render things in opengl. We worked on it pretty consistently over the years, including me working on it full time for about 8 months. That having been said, if we were to start the project over right now we could probably do it in about 2 years. None of us had ever developed a game before so we had lots of missteps and wasted effort along the way.
-i do plan on making a mac port, im not sure when I will get around to it.
As for Phys2D, I wouldn't recommend it. Its an old library that is no longer supported. If you are looking for java2d physics I would recommend Jbox2d or Fizzy.
Having programmed our game from scratch I would say my biggest take away from this project is the following. If you want to learn about game programming than go ahead and program everything from scratch. However, If your goal is to develop and market a game for profit, use a professional engine, I would recommend unity. The time spent during the development of Titanis was probably about 85% programming, and 15% game/level design. We were also plagued by countless low level bugs/problems that you would never have problems with in a professional engine.
Thanks for the interest in our game!