333k with outstanding reviews (game of the year) released in the holidays, and therefore sold a whole lot in the following weeks, and also got two re-releases. also, remember that it had a staggered release because it got recalled in america for that stupid song. take a good long look again at it's sales, not just first week. as you mentioned already, LBP was hyped like crazy. hence the sales. and the only people who said that LBP flopped were those who predicted the insane 10 million sales.
not a comparison to modnation, which received mediocre reviews (82 metacritic), released in the slowest season of the year, and is not hyped by any means. it will not receive a platinum treatment, nor will it be game of the year (no way). where's the marketing push? none. where's the hype? none.
don't compare a good game and a mediocre game just because they have the same concept. modnation is a flop, and there's nothing anyone can do about it. second week sales WW should be below 100k. third week should be around 60k. then it'll disappear into obscurity.