I just received a mailing-list email from OddLabs where they state:
Sad to see that have happened - it was a decent RTS (I helped beta-test the first game in the series on Linux a few years ago) but apparently they never got to manage enough traction. Another Linux game that ended up in that fate. Then again, the list of Windows-only games that share that fate is looooong!The legacy of Tribal Trouble
We had a great time with Tribal Trouble, but unfortunately we have not been able to make it economically viable. When it was time to shut down the server, we decided to release the source code to the masses, in hopes that the game will never be forgotten. Oddlabs will not be putting more time into Tribal Trouble, but if you want to give it a go on your own, you can find the source code here.
Regardless, it is a professional-quality (even if that doesn't mean better than the likes of Spring) RTS made open-source. I wonder how moddable it is. I do know it is multi-platform and it written is in Java (at least for the most part) invoking native 3D acceleration, which makes it kind of similar to the planned re-write of Spring, which was inclined to be in .NET invoking native 3D acceleration.