It requires that you register to update.  You can play the version on the disk without even having a key.  To update, you'll just have to register it with impulse, at which point yes, you can still install it from the disk.  I do so myself regardless, it's quicker than downloading the entire thing.

So, if I don't want to update I don't have to register? All the Trinity edition content is on the disc and installs without any DRM? AWESOME!

Thanks guys!

P.S: Is this the same with GalCiv2 Ultimate? (I don't wanna create a whole new thread in another forum to ask a similar question)

Thank you so much!

/adds both to basket

Edit: Is there any other games that have this type of "not-DRM"?

Most Stardock published games have this sort of system. The disk you buy has no protection whatsoever (you don't even need it in the CD drive), but to get patches and support they want to know you are an actual customer. I assume Demigod is also this way, though as mainly a multiplayer game it isn't as much of an advantage.

That said, you really should register and get the updates regardless. Mods and multiplayer typically require the latest patch, and you can completely uninstall impulse after you are done updating. And should the internet for some reason catastrophically fail at the same time your hard drive dies, you still have the version on the disk to install on a new computer.