I already have my wishlist which can be found here:
http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Main=27954&Number=450451#Post450451

Since this game is a prequel, most of the suggestions I made cannot be implemented. To summarize and without including the sequels, here's the list (I'll cross out what is going to be implemented):

Mini-games - There's a fishing rod, a harvest moon kind of fishing game could be nice.
Romance or relationship development - dialogue interactions w/ your companion implements this

Mind reading - Source hunters can also mind read too?

Hunting we shall go - Phantom forest seems to implement it.

More "plays" - I hope the 400k stretch goal will implement more quests like this.

Battle tower companions - Shelter at plane homestead implemented this.

Side quest consequences - It happened when the fire of the burning ship in cyreal got extinguished and people celebrated it. I know other parts of the game will have this.

Good ending/Bad ending choices - self explanatory. increases replayability.

In addition, Kirill sidequest could be nice.

"There is no such thing as absolute freedom because we are still prisoners of society"