Games that i tested today and that work:

Skyrim (needs dll-overrides)
Gothic III

can any game be played under wine on a linux system?

Games i Played on WIne (i probably not remeber all but this i my list)
In previous post i say:
Medieval Total War II
But i play others like:
Dead Rising 2 -> Works all
Prototype-> need rename movies.rcf to other some name(if dont rename the game dont works) works without sound.
Assassins creed-> played slowly all works.
Far cry-> All works.
Flatout2-> Amazing works.
FIFA 99-> WOrks very well
F.E.A.R Perseus Mandate -> Amazing works.
Panzer Killer-> Amazing Works
Need for speed Most Wanted-> Amazing works.
Call of Duty 2-> Amazing Works.

Ok im used an ATI graphic card to the game Flatout2 Works well you need install last drivers, if not the game presents to you a message-
Failed to load /data/Database/FlatOut2.db.

In my blog Tux-a-Solta i post some cases of how i install some games on my Linux, im use Ubuntu but also others systems.

For Ubuntu you have a extremely page with games with Free use the page is Playdeb.

Greetings.

I had play War3 in Linux,under wine.

I got Farm Frenzy working using Crossover which in turn uses Wine.You can download it free from Myplaycity.com.The graphics on the completion scene were a little messed but the game worked perfectly.