Unfortunately the acquisition fell through but the development team had already finished coding the Easter egg into the core code. The Easter egg addition was long forgotten and was never removed from the core Excel code but can still be access during the Excel loading screen.
While Excel is loading press Up, Up, Down, Down, Left, Right, Left, Right, B, A on your keyboard.
If you entered the code correctly during start up, you will be able to play Contra from within Excel. Wow, so much fun! Happy April Fool’s Day!