According to the C++ standard the float and double overloads for the std::abs() function are defined in the “cmath” header. Looks like you either forgot to include cmath or to use the std namespace — otherwise abs() should have worked as expected.
Anyway, if those two examples were your worst portability issues you did an incredible job writing portable code in the first place! The game runs flawlessly on my 64-bit Fedora 18 machine.
Thanks for tip with cmath and kind words. Glad to know that the game is working.
Porting was fairly easy, wasnt it? Good job from you. Grimind is an interesting game, I liked the physics/controlling the character, but you need to work on audiovisuals (or consider collaboration with some kind of artist).
Yes, it was quite easy because of great multi-platform libraries I use.