Looking in the Steam store, the Sims DLC packs have a little banner similar to this:
Requires the base game The Sims™ 3 on Steam in order to play.
My girlfriend has Sims 3 and Sims Medieval through Origin, and was hoping to get the DLC through Steam to take advantage of their sales. Is there any way to get the Steam DLC to work with the Origin base games? I would assume the files are mostly the same and some combination of file copies, editing, and registry changes would work, but I'd like to find out for sure.
Edit: I'm still interested in the answer even if I'd need the Steam base game in order to buy the DLC. I'm also interested in the reverse — can DLC from Origin be used with the Steam base game?
Best Answer
It works one way, but not the other. You can use the keys gained in Steam (Right click on game in left-hand menu, View Game CD Key) and activate them for your EA Games account by registering them at https://activate.ea.com, which makes them then appear in your Origin games list for installation. (This applies to most - but not all - EA Games that are available on Origin)
You cannot use Origin codes to apply games to Steam, and Steam won't let you buy DLC for games you don't own though Steam.
[2015 update: You now activate them on Origin though the client. Origin menu, Redeem Product Code.]