Empire: Total War Heaven

Unless the person you bought the game from gives you his/her Steam account details, you won't be able to use that copy.

Steam has a Total War sale on at the moment, so you can get a working version of the game pretty cheaply - 13.59 USD. But if you don't have the earlier games, you can ETW with them in the Total War Mega pack for 20.39 USD.

Sorry WarsmithHonsou but you've been robbed by the seller.

As Pitt said, ETW works via Steam and the game is locked to your account when you install it. That has a number of advantages such as:
-Being able to re-install the game even if you lose the discs.
-Being able to install the game on multiple computers as long as you log in with your account.

However, one of the downsides is that you can't loan or give the discs to a friend for them to play unless you give them access to your Steam account as well.

Not all PC games require Steam so just be careful in future that a game isn't locked to a single user before you buy it.

I personally think this is stupid, and that Steam have done a very good job of killing the second hand market. How hard would it be to allow a user to de-register a key when they uninstall a game, so that if they sell it to someone else, that person can use it?

Two things I'd like to see added to Steam.

1. The ability to give/sell a game to somebody else. Steam could make a tidy sum by taking a small cut of the sale value. That's my advice for free lads!
2. The ability to loan a game to a friend for a limited time period.