Hi! I'm Daniel, one of the developers at Trello.
In the beginning of 2013, Trello celebrated its 1 millionth signup. We created a special landing page1 to announce that fact, and I wrote a little game to include as an easter egg.
Not quite two years later, Trello had its 5 millionth signup and I thought it'd be fun to keep with tradition and hide another little game in our announcement.
For years I've been hearing comments about how Trello kind of looks like a game, if you stand far away and squint your eyes a little bit. Taco Out! is a game2 that kind of looks like a productivity application … Trello!
So enjoy! And don't forget to get back to your actual cards; Trello is supposed to help you be more productive!
1 The "1 million!" page has since been taken down, but the little game lives on.
2 … obviously inspired by the Atari classic Breakout, as well as all the pixely games of my childhood.