FG is a single developer. One thing to update, no conflicts. Foundry VTT is the core platform, 300+ game systems, and 3000+ modules,
No. FG has a very active community of unofficial developers like Foundry does. You can check out the FG Forge at
Fantasy Grounds Forge All of those are not created by the FG developers (SmiteWorks). If you use extensions or rulesets (code modifications) from the Forge, you can run into the same problems as happens with Foundry modules.
It's just that FG has a lot more base automation and DLC content that is officially supported via the FG Store,
Fantasy Grounds Store - VTT modules
Just to make sure we're talking the same thing, I'm referring to the VTT needing to access nothing but itself, the Net itself, and the other machines in use. Is that what you're saying? Because if so, that's literally not only not come up a single time before, I've seen conversations that seem to imply quite the opposite. This is not me suggesting you're lying or incorrect, its just me being boggled this is the first time I've seen suggestions of this.
(To be doubly clear--does it even need to "phone home" on startup?)
So I'm not totally clear what your understanding is.
So FGU is installed local to the GM/Host computer. There are two ways the host can set up for players to connect. Either through Cloud brokering (i.e. a semi-public server that does the match making and negotiates the connections between the clients and the host), or via a direct LAN mode where port forwarding might be needed depending upon host networking.
The Cloud brokering does need access to the FG servers to broker those connections, but if it is able to establish a direct peer to peer connection it does, and then it does not handle the traffic etc.
Now, the other time that FGU connects to the FG servers is to validate licenses. This is only done when a free/demo player connects and only at the time the game is joined. If a licensed player connects, not license validation is done.
So, if you are running on a stand alone network (no internet) then you need to use a LAN connection and all players that connect need to be licensed since license validation won't work. I know of several regular gaming groups that run this way on naval ships and such where no internet is available.
Does that clear it up?