Crassmaster: The only Steamworks features it's actually utilizing are auto-updates and multi-player. So yeah, the CK2 method of running the game right from the executable without needing Steam running should still work. You will need Steam for installation, DLC installation and updates, though.
Gersen: CK2 was DRM-free, unless they changed their mind since the initial announcement (that the game wouldn't be available DRM-free) it was strongly implied that the game would require Steam not just being distributed on it.
Anyway unless there is an official post from the devs that the game will be playable on a Steam-less PC there is no real way of being sure of either before the actual release date.
Yes, it will require Steam to install, and to install DLC and get updates. If you want to play it without using the Steam client, that will still be possible. It will also be possible to move the entire game folder somewhere else on the drive and run it completely independently.
Here we go, a post by one of the devs (scroll down a bit to see Tegus' post) :
http://forum.paradoxplaza.com/forum/showthread.php?659511-Have-to-download-through-Steam-%28for-devs%29/page4&s=5cdf788d7aa76493b925e2fb74363472 [i]My two cents:
For those of you who dislike the Steam auto-updates out there(or maybe Steam altogether). Please note that Steam is only required to install the game, but not required to run it. Steam can be configured to also act as a DRM for games, but currently we do not use this feature for our games(and there are currently no such plans in motion that I'm aware of).
In essence, this means that you could do the following if you really, really, hate Steam:
1) Get a separate computer with internet connection
2) Register Steam under an email which you don't use anywhere else(with a unique password)
3) Install your Paradox game of choice
4) Copy the game from the Steam folders to a USB stick
5) Format the computer to obliterate all traces of Steam
6) Copy contents of the USB stick to the computer you want to play the game on
7) Mark stick with current version number of game and store it somewhere safe
8) Optional: If you want to get the latest patch, goto step 1.
Now, this is of course a lot of extra hassle to play our games, but it is an option. One of the reasons we as devs want people to use Steam is that Steam forces everyone to patch, which ensures that everyone that contacts us for support are guaranteed to run the latest build of our game. From our point of view, this is a really good thing.[/i]
A bit later on that page, he explains that you will need to load the game up once through Steam to get any newly added DLC to add, then you can again play untethered to Steam with full access to the DLC you've purchased.