It is a reference to both the 20th anniversary of ScummVM and the opening text in Maniac Mansion, the first SCUMM game.

That's probably the reference in this case, but it's also the opening line of "Sgt. Pepper's Lonely Hearts Club Band" by the Beatles, which I suspect might have popularized the sentence? Or is it just a very common idiom in English?

Sgt. Pepper might have inspired Ron Gilbert to use it in Maniac Mansion, but we took it from Maniac Mansion for the 20th anniversary :)

I googled the phrase to make sure we quoted Maniac Mansion correctly and that’s when I realized it was probably a Beatles reference originally.