In an open letter posted on the Hitman website, the studio said the game will star a globetrotting Agent 47 in the prime of his career, fulfilling contracts across "huge, checkpoint-free, sandbox levels" with the support of the ICA and long-term handler Diana Burnwood.
IO, which plans to reveal more about the title later this year, said on Thursday:
"The game concentrates on the core Hitman fantasy of using a wide range of tools to take out a diverse group of targets across expansive, exotic locations around the world.
"We are building this game on the backbone of the Glacier 2 engine, using the best parts and what we have learnt through Hitman: Absolution and drawing inspiration from past titles like Contracts and Blood Money to fulfil the core Hitman fantasy.
"That means we're packing in an extreme level of detail on the largest levels we have ever built for a Hitman game. We've adopted an open, non-linear level design approach to the game, ensuring the game will play out across huge, checkpoint-free, sandbox levels.
"Our aim is to create living, breathing and believable levels which will allow gamers to play around with the AI to create those unique moments every fan of the Hitman franchise loves."
Contracts Mode will return in the new game, enabling players to create and share their own custom challenges online, while Agents 47's "magic pockets" have been removed, perhaps paving the way for the return of his weapon carrying briefcase.
The first details about the project arrive a few weeks after Hitman publisher Square Enix addressed reports claiming it had canned a triple-A Hitman title previously in development at Square Enix Montreal.
In a statement which didn't deny that a Hitman title has been dropped, the company said on January 6:
"IO Interactive is developing a new, AAA Hitman game that will be coming to PC and next-gen consoles and Square Enix Montreal is fully focused on mobile development of games some of which are related to the Hitman franchise. We look forward to sharing more details about these titles later this year."