Mod Situations

#1 First, you'd want to read a EULA before making a decision on any engine. It is a factor like any other (graphics, interface, et cetera) because it frees or limits you in the same manner as any of those other factors.

As for giving others V12 tools for modding purposes, it depends entirely on what kind of tools you're giving them. With respect to Tribes 2, most everything you can do with the game is through scripting and custom modeling. By that rationale, as long as you're using the same general guidelines with respect to scripting and the malleability of said scripts, you should be okay. If, however, you're looking to give them some ridiculous amount of power that goes well beyond scripting (such as recompiling the game from its original source code), you'd probably be looking at a legal brick wall there, since you can't distribute the V12 source code (since only GG can do that).

After all, my project is solely dependent on modifying the V12 source code into a state that's more conducive to social environments, rather than creating a shooter. Granted, there will be scripts for combat and such, but I'm not going to go and allow people to mess with the proprietary commands that I program in, since they'll be embedded in the source. Essentially, my plan is a rapid-development game-kit for creating graphical role-playing games and allowing the server/Admins to create the world itself. I just provide various things that need to be hardcoded for functionality, some optional softcode (modifiable scripts) for flavor, and they get to create the worlds. The only thing I'm making is a mock-up of Denny's so I can chat with other people's avatars. Mock my idea if you will, but take a look at how many text-based multiplayer RPG's there are on the net, and look at how different they are. Similar code-bases, wide variety. I want to provide variety and social interaction rather than contributing to the stagnation of gaming as we know it.

But I digress. If you allow script-modifications and custom models, you should be fine. Anything above and beyond that, you might have a problem.

#2 Custom models includes levels I'm guessing, so does that mean I can give out the indoor/terrain editor that comes with the engine?

And I have read just about everything but the EULA, amd I'm doing that now.

#3 You can not release any of the source code that comes with the v12 or its upgrades. You can however share the compiled tools and any scripts, models, and missions you create. In fact, I believe the plan is to release a compiled version of the v12 so that people can create mods off of it so I can't see how you would get into any trouble by making your game modable in the same way as long as you don't release any of the v12's source code.