With New Zealand having reached the finals for the first time since 1982 and for only the second time in their history, the Middlesbrough forward is determined to make the most of the experience, starting with the group F encounter with Slovakia on Tuesday.
"It's got to be one of the biggest games in the history of New Zealand football," Killen said. "The first game in any tournament is always hugely important and that's particularly true here. We know Slovakia are a good side but so are Italy and Paraguay. We need to get something out of this is we want to get through the group."
Kiwi hopes of making a mark on the tournament have been raised by an unexpected 1-0 win over highly-rated Serbia in a warm-up friendly in Austria earlier this month. Killen missed that match in order to fly to Scotland, where he married girlfriend Hannah on the banks of Loch Lomond.
"It was a great day and it would have been nice to go on honeymoon straight afterwards," admitted the former Hibernian and Celtic striker. "The missus would have been happier with that but she knows how important the World Cup is to my career."
Slovakia, who are making their first finals appearance, have also identified Tuesday's encounter in the Royal Bafokeng stadium as crucial to their prospects of reaching the Round of 16.
Coach Vladmir Weiss made it clear he regards the match as one his squad should expect to win and has promised an attacking approach. "We'll be going for a win and the three points that will get us off to a good start," he said. "Anything less than that will makes things more complicated for the remaining games. New Zealand is a tough opponent but I think we have more quality in our squad."
Slovakia had an impressive qualifying campaign in which their 22-year-old captain, Marek Hamsik, who plays for Serie A side Napoli, was the standout player. The New Zealanders will also be wary of VfL Bochum striker Stanislav Sestak and Miroslav Stoch, a tricky winger who spent four years on Chelsea's books.
Stoch, 20, has shaken off a knee problem that had threatened to rule him out of Tuesday's match and enters the tournament on the back of a fine season on loan at FC Twente, who he helped to the Dutch title before agreeing a 2.5-million-pound move to Turkish giants Fenerbahce.
Slovakia defender Martin Skrtel is set to play after recovering from a minor ankle injury he suffered last week, although there is a question mark over the match fitness of the centre-back, who missed the last three months of the English season with Liverpoool with a broken bone in his foot.
New Zealand captain Ryan Nelsen has recovered from an ear infection and will lead the side but vice-captain Tim Brown, who underwent shoulder surgery at the end of May, is not expected to be risked before the squad's second match, against Italy in Nelspruit on Sunday.