TWRoO on 26 January 2008
Yes, you can register any code, doesn't matter when you bought it... I only added mine after Christmas but I found a slip in Chibi Robo which I bought about a month after it's launch (2005 I think)
Shame you don't get it in Australia, I am sure I remember someone saying they had bought games in Aus and wanted to know if they could be added to the UK site.
