Baywatch star David Hasselhoff and Borussia Dortmund footballer Marco Reus both appeared in virtual form as the Gamescom video games show began in Germany.
The Knight Rider actor appeared as a DJ in a 1980s disco and theme park-based Call Of Duty "Zombies In Spaceland" experience, which was unveiled by the game's publisher Activision. German international Reus is the cover star of FIFA 17, EA Sports' latest version of their smash hit football game.
The midfielder appeared at a pre-show event where he played the game alongside YouTube stars including the UK's Spencer FC.
Gamescom opens on Wednesday, with fans given the chance to experience and try out upcoming games, including Call Of Duty: Infinite Warfare, which launches in November, for the first time. The zombies spin-off levels of the game have become increasingly popular with fans, having started as a hidden level in early versions of the franchise.
Brian Bright, project director at Infinity Ward, the game's developer said: "Call Of Duty and zombies in particular has such an incredible history with passionate fans, which inspired us to take all the co-op action that has made the series so great and fuse it with one of our favourite decades in pop culture: the 80s.
"Zombies In Spaceland is an all-new zombies experience where day-glow meets fright nights. It's accessible for new players, but also has a deep layer of progression, brimming with easter eggs and various game features that will be a blast for hardcore zombies fans. We can't wait for fans to go hands-on this fall."
More than 300,000 visitors are expected at the show in Cologne, where a range of games, also including Electronic Arts' Call Of Duty competitor Battlefield 1 - set during the First World War - will be playable for fans for the first time.
Activision's Destiny franchise, which is receiving an expansion in September called Rise Of Iron, is also expected to be popular among show-goers having built up a loyal following since its launch in 2014.