On February 5, 2010, the UK-based Nintendo magazine NGamer reported on their Twitter account that, according to a trusted source, Sonic the Hedgehog would be a playable character in Super Mario Galaxy 2:
"We've just had some shocking news from an inside source at Nintendo: Sonic will be a playable character in Mario Galaxy 2! Wha?" - NGmer Twitter
About two hours later, they posted another tweet explaining that he would be playable in a "Green Hill Galaxy".
"More teasing from our insider: Sonic levels will be in 'Green Hill Galaxy'. Matthew's nearly in tears (of despair)" - NGamer Twitter