Classic Concentration (NES)
This game has unused graphics.
The NES Classic Concentration is based on the game show of the same name, which at this point was close to the end of its run (first-run episodes stopped in September 1991).
The front-game format here is a watered-down version of the show's "first to solve two puzzles plays the car game" style (the more gimmicky cards that were in use at this point, such as TAKE! and Cash Pot, aren't present), which had been replaced by a "two losses and you're out" format shortly before this game's release.
An unused graphic for the developer, Softie, is present in the ROM.
It should be displayed on the title screen along with the Nintendo logo, and you can see how it should be using the Game Genie code GEKNLKOP. However, Softie's credit is smaller than Nintendo's, resulting in them overlapping.