Call of Duty: Black Ops 3's last-generation versions will only include the Black Ops series' traditional Zombies and competitive multiplayer components — no single-player campaign, publisher Activision announced today.

The reason? The campaign is too "ambitious" for the old consoles to handle, according to the company.

"The ambitious scope of the 1-4 player [co-op] Campaign design of the PS4, Xbox One and PC versions could not be faithfully recreated on old generation hardware," said Activision. "Delivering the best possible gameplay experience on all platforms is always our highest priority."

Black Ops 3 on PS3 and Xbox 360 is being developed by Beenox and Mercenary Technology; the current-generation versions are being made in-house at Treyarch. When Activision announced the PS3 and Xbox 360 versions in June, it said the co-op campaign would be available on those platforms, but noted that they would only support two players, not four.

The old consoles will still get the new elements coming to Black Ops 3's multiplayer component, including the new movement system and the nine different Specialist classes that players can choose from, as well as the 1940s Zombies adventure, "Shadows of Evil." But other features designed for new hardware, like the Weapon Paint Shop and eSports tools, will be restricted to the PS4, Windows PC and Xbox One versions.

To reflect the pared-down feature set, Black Ops 3 on PS3 and Xbox 360 will be priced at $49.99 instead of $59.99, and will come with a downloadable copy of the original Call of Duty: Black Ops from 2010.

For more on Black Ops 3, check out our preview of the co-op campaign, and our hands-on impressions from E3 of the multiplayer component.