343 Industries is busily working on the next Halo game, which is codenamed "Infinite".
Halo didn't steal Microsoft's E3 2018 press conference like I had hoped. Instead of a triumphant demo that caused explosive yells from the audience, 343i showed off an engine tech teaser for its newest Slipspace Engine, which is powering the latest Halo project. Halo Infinite will continue Master Chief's journey past Halo 5 and should round out the Reclaimer Trilogy.
"In Halo Infinite we will join Master Chief on his most epic journey to save humanity," said Xbox division head Phil Spencer.
"At E3 2018, 343 Industries officially announced that the next chapter in the epic Halo saga is in active development - Unannounced Halo Title. Unveiled through a thrilling engine demo, Unannounced Halo Title will be a new Halo experience centered on the Master Chief that continues the current storyline," reads the Xbox Wire post.
It's likely that Infinite has been in development for some time--ditto for the Slipspace Engine--but Microsoft and 343i haven't officially confirmed or announced anything up until now.
Infinite should be the next mainline Halo game so it's fair to say it should be a shooter...but at this point we never really know what 343i will do next.