To celebrate the first anniversary of Killzone 2, we're giving away four hundred DLC voucher codes via Twitter - one hundred for each Killzone 2 map pack, and another hundred for the full DLC bundle, including all map packs and multiplayer weapon!

Please note that you will need a Twitter account in addition to your PSN Online ID to participate in this giveaway promo; you can sign up here if you don't have one yet. And don't forget to read the official rules below before you start tweeting away!

1. This promotion is open to residents of Australia, Austria, Canada, Czech Republic, Denmark, Finland, France, Greece, Ireland, Luxembourg, Netherlands, New Zealand, Poland, Portugal, Russia, Saudi Arabia, South Africa, Spain, Switzerland, United Arab Emirates, United Kingdom and United States aged 18 years or over.
    
2. To enter this promotion, mention @killzonedotcom during the Promotional Period with the following message:
   
   "@killzonedotcom Happy birthday Killzone 2! [your PSN Online ID], [your country]"
   
   The message must be in English.
    
3. This promotion opens for entries on 26-02-2010 at 18:00 GMT and closes for entries on 05-03-2010 at 18:00 GMT ("the Promotional Period").
    
4. Entrants will need to create a PlayStation Network account ("PSN account") if they have not already done so. Registration for PSN is subject to acceptance of the PSN Terms of Service and User Agreement and PSN Privacy Policy. Entrants will also need to have a Twitter account. The Twitter Terms of Service shall apply.
    
5. This promotion is limited to one entry per person. No entrant may win more than one prize.
    
6. The winners will be drawn randomly from all eligible entries received during the Promotional Period. The draw will take place within 30 days of the closing date specified above.
    
7. The Prize is a PSN promotion code for one Killzone 2 map pack or one Killzone 2 DLC bundle. PSN promotion code terms and conditions apply. PSN promotion codes are subject to terms and conditions of use. Please click here for details. PSN promotion codes are not transferable and may not be re-sold. No cash alternatives will be offered. PSN promotion codes have an expiry date which will be communicated with the code.
    
8. The Winners will be notified via the e-mail address associated with their PSN account within 30 days of the closing date. The Winners must claim their prize within 10 days of the notification. Prizes shall be sent by e-mail.
    
9. The Promoter may, at its sole discretion, publish the winners' PSN IDs name and country of residence on the Promoter's website(s). The winner's details (name and country) will be made available on request to those enclosing a stamped SAE marked to the following address: Killzone Marketing Team, Sony Computer Entertainment Europe Limited, 10 Great Marlborough Street, London W1F 7LP, United Kingdom within 2 weeks of the closing date specified above.
    
10. General Rules apply to this promotion. Please click here to view the General Rules.
     
11. The Promoter is: Sony Computer Entertainment Europe Limited, 10 Great Marlborough Street, London W1F 7LP, United Kingdom.