Q: Is OGRE really free? If you abide by the open source licensing conditions, yes.
Q: Do I have to release my own source code if I use OGRE?
Q: Do I have to release changes I make to OGRE?
A: From Ogre 1.7 we use the MIT license, which does not require you to do this. However, you should consider the maintenance overhead of keeping your own custom version of OGRE, versus the advantages you might get from participating in the community (such as bugfixes and extensions that others may make on top of yours).
Q: What do I need to do to abide by the MIT license?
A: Simply include our license text somewhere in your own software distribution; this could be in a text file, in a printed manual, in the credits, etc.
Q: Do I have to display an OGRE logo in my application, in splash screen or startup sequence for example?
A: No, although we appreciate the publicity if you would like to do this!
Q: At what point do I have to ensure that I’ve complied with the license?
A: When you distribute any part of your application to a third party.