Bethesda Softworks released the trailer for its upcoming video game "Indiana Jones and the Great Circle" on Thursday, and fans couldn't help but notice ... Indy sounds a bit different.

That's because Ford -- who played the role in all film/TV content -- isn't lending his voice to the project ... instead it's Troy Baker, who's kinda like the Harrison Ford of the video game world. Yep, he's that iconic.

Just check out the guy's credits ... "The Last of Us," 'Mortal Kombat,' "BioShock," "Halo 4," 'Resident Evil' and "Call of Duty: Black Ops" ... plus he voiced freakin' Batman in one series!

And, fan reactions are .... overwhelmingly positive (not a small feat when it comes to the gaming community.) People who know Baker's work love the casting and those who don't were still blown away by the trailer - 'cause he's doing one heck of an impression.

It's unclear exactly why Harrison isn't coming back to the role. Could be money -- video games don't have the same budgets as blockbuster films -- or it could be that Han Solo's keeping to the promises he made during his press tour for "Indiana Jones and the Dial of Destiny" ... namely, that he's finished with Indy, and he's moving on to bigger and better.

One such quote that really says it all ... when asked if it was bittersweet leaving the character HF replied, "No. It’s time for me to grow up." So, it definitely sounds like a dude who's hanging his old archeologist's hat.

Harrison's got other roles to kick ass at BTW ... he just received a Critics Choice Award nom for his work as Dr. Paul Rhoades in "Shrinking," and he's got two Marvel projects on the way -- dude's pretty busy for an 81 year old.