After Titan Quest Anniversary Edition has been released earlier this year, THQ Nordic stated that the game is now available on Windows 10 Store, too.

Link to Titan Quest Anniversary Edition on Windows 10 Store: http://n.thq.com/5DrI3076UtB

Titan Quest Anniversary Edition contains both Titan Quest and Titan Quest: Immortal Throne which have been completely reworked in terms of multiplayer, stability, performance, balancing, AI and much more. In numbers, this translates to roughly 1.261 changes to the original version 10 years ago. 

For the detailed changelog, refer to this link: http://titanquestgame.com/pcchangelog/TQ_AnniversaryEdition_FullChangelog.txt