At the moment there are two distinct modes, Classic and Equipped. In classic you get a random staff and the spells are random.
In equipped you can pick your staff which influences your spell hand and you can also bind spells to your staff to make sure you get the ones you like.
I have been playing various versions of Chaos regularly for over 28 years and it is really the randomness that keeps it fresh and ensures each game requires different strategies.
Chaos however is far from a game of pure luck, it is similar to p0ker, managing risk, bluffing and tactical positioning. Just as in p0ker people who are new to it may say it is just a game of luck, however the most skilled players rise to the top.
And it is great value for money, sure you can try it on Steam and if its not for you, you can get a full refund, so win win really!
Just for the record I am in no way gaining monetarily from promoting this.
I am a hardcore gamer who loves all types of computer games, love Chaos to bits and just really want it and Julian Gollop to get the success and acknowledgement that they so deserve.
And cant blame you for finishing up New Vegas, I can barley contain my excitement for Fallout 4 as I believe 3 is probably one of the best games ever made (along with XCom and Chaos of course:) and hopefully 4 will surpass it in every way!