We've discovered a sneaky Easter egg hidden in Wolfenstein: The New Order that allows you to play some of the series' 22-year-old classic Wolfenstein 3D, re-made in the game's engine.

Eurogamer's YouTube editor Ian Higton spotted the retro mini-game early on in The New Order's campaign. By taking a quick nap in a safehouse bed, you suddenly awake in a 16-bit "nightmare".

The Easter egg itself looks like it'll only be playable the once - when Ian died he awoke from the mode and was seemingly unable to return - so a quick save beforehand is recommended.

Apart from the Easter egg itself we've kept campaign spoilers to a minimum, but if you want to stay entirely spoiler-free then bare in mind we show a small portion of the level directly before the Easter egg is discovered.

And if you haven't already seen, we've just published our Wolfenstein: The New Order review - take a gander at that if you're thinking of a purchase.

Watch us explore the Wolfenstein 3D Easter egg below, or subscribe to Eurogamer's channel on YouTube to watch it there: