The World of Avlis

If I install it, will I still be able to play Avlis?

Yes as long as you install it as additional hak and do not try to "upgrade" the haks currently installed. By default cep2 files should not try to replace the cep1 files anyway.

Wait for some other replies to confirm this as I'm not 100%. If someone plays with ver 2.0 they can confirm or deny. But I believe that 2.0 is backward compatable, although you will see some very different stuff, some of it wonky, then everyone else without 2.0 installed. So, I do not think it will stop you from logging onto Avlis, but it may make gameplay a bit strange, unpredicatable or even unfun (missing inventory items, invisible unselectable creatures, the occasional crash, etc..).

I have both installed and I have no problems.

Great, thanks!