Tips for avoiding posting art that’s already been posted:
Use the magnifying glass search button in the upper right to search the thread for the title of the game of the art you’re thinking of posting
Once you’ve checked any previous posts matching your game’s name to make sure the art you’re thinking of posting HASN’T been posted already, when you post it, be sure to put the game name in your post, too! : D
Concept art usually refers specifically to illustrations produced as reference for the production of game assets–as the first post in the concept art thread mentions. (Ooh actually “reference art” would be more specifically character model sheets and so forth, so that could be its own OTHER thread if someone wanted ; ]–@shelter in the concept art thread put it better about actual concept art: “can be schematic/mechanical design/area and environment design/character concepts, etc.”) I’ve added concept art and the link to that thread to the list in the OP of art types that go in other threads.
As far as I know we didn’t yet have a thread for illustrations produced of the game itself, if they weren’t box art. So, like, I found v that Strider 2 illustration a few weeks ago, but didn’t have anywhere to share it on sb.