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I downloaded the 2.3.1 patch (game version 1.3), but when I start the game it says:

"A New Version of Rise of the Triad is now available! Download it from, or Steam!"
There is no announcement of a new patch on Steam yet. The developers do say that 1.4 is coming soon. My guess it that it's an "accidental" flagging before the update was actually released.