Telltale have been very busy lately, in-between signing deals with Netflix and tussling with their former CEO. The studio that (gradually) popularised episodic games has a lot on their plate, and now they've got a pretty heavy dessert lined up for once they've finished the upcoming fourth and final Walking Dead game season. According to anonymous sources speaking to Variety (and somewhat supported by job listings), the studio are retiring their long-lasting but occasionally wonky in-house Telltale Tool engine and moving over to Unity.
The Telltale Tool engine did last the studio through a great many games, including the remarkably charming (and sadly no-longer-sold) Wallace and Gromit series, but reportedly it was never that easy to work with. While I wouldn't exactly be surprised that the studio is moving to Unity (on account of Unity's CEO John Riccitiello on their board of directors), it's a good pick. Powerful, flexible and rapidly growing, and should make porting to other platforms a bit easier.
While those of us with decent-spec PCs were spared the worst of the horrors, Telltale's engine has suffered from a plethora of nasty issues over on lower-end systems, and especially on consoles, with framerates plummeting during key action-focused sequences on the Xbox 360 and PS3 in many cases. And while the precise cause is unclear, save corruption bugs have been a recurrent problem robbed him of much of his enthusiasm for The Walking Dead series.
A move to Unity would of course bring its own set of challenges, hence why they're hiring in additional talent to help with the transition. Variety's sources claim that Telltale's Stranger Things game will be their first game on Unity.