jamotide: Maybe the game had not a single sale, so no need to update :D
I bought it! And I actually re-installed and tried it again some weeks ago, played it a bit.
Besides the new levels, what is missing in the GOG version? I recall when i tried the game the first time one or two years ago (don't recall which), I found some note on a tree which apparently lead to some secret mission or level in the game, which was apparently missing in the GOG version. Not sure if that has been added or fixed then, apparently not.
Has GOG said anything about the status? E.g. has GOG just forgotten to remind the developer to patch it up, or has the developer outright declined further support for the GOG version? Is the developer still around to patch the game up?
From my memory:
Deadly Premonition: Was it so that GOG version is missing some final patch, which isn't that necessary though? At least it seems to have received some update(s) since I tried it earlier, because now the GOG version seems to support the XBox360 gamepad properly (earlier it was unplayable with a gamepad IIRC, but fine on mouse+keyboard). And that the publisher has stated the developer team is already abolished, so no more updates to be expected to either the GOG nor other versions?
Rise of the Triad: Was it so that the publisher flat-out said they will support only the Steam version from now on? Not sure if the GOG version is missing any important fixes, at least the GOG version feels fully playable the last time I tried it.
In a way, I feel if the publisher makes the decision not to support the GOG version anymore, then they should pull it from the GOG store themselves. Like happened with ARMA2 I guess. At least then it is clear where the publisher stands regarding the GOG version, and they aren't pretending to support it anymore.