Valve writer Chet Falliszek has told Videogamer that Portal 2 will feature two end credit sequences, one for single-player and one for co-op.
Both credit sets will also each feature a surprise.
"Both sets of credits [will feature something special], because we've got two credits," Faliszek told the site.
"So we had to do something twice as amazing."
There will be more additional surprises in the game, but Faliszek wasn't spilling.
"The cool thing is that we'll make sure that the game doesn't get too difficult. It's more complex, but it's never so difficult that you can't solve it. You'll get to the endings. We'd hate to think that people would only watch the endings on YouTube.
"It's scary actually - the ending to Portal has over 5 million hits on YouTube."
User-made levels confirmed for all platforms
Faliszek also confirmed to NowGamer that the title would include user-made levels for all platforms. Including the usually-closed 360.
"The mod tools have to stay on the PC side just because there’s a bunch of dependencies that require the Windows platform," he said.
"But the content that comes out is agnostic, and so we will be seeing that on all the platforms. Depending on the platform you’re on I should say, will depend on how we’re delivering it."
He added that PS3 users would get said levels through Steamworks.
"There’s just a lot of value in engaging the community because they’re smart, they’re thinking of really cool things and we want to be able to have everyone share that."
Valve announced last week that the game would feature cross-platform play between PS3 and PC-Mac versions, with the former featuring a SteamPlay of the desktop version.
Portal 2 releases on April 22 on PS3, 360, PC and Mac.