Ah, the arcade. A sanctuary for the juvenile delinquents of Detroit. Unfortunately, I don’t see a Bubble Bobble cabinet anywhere, and RoboCop came out before Metal Slug even existed.
Nonetheless, in RoboCop: Rogue City, you visit the arcade looking for Soot, the leader of the Torch Heads gang. After getting a warrant to investigate, you head to the basement. The gang isn’t interested in talking, so they just fire on the robo-knight in shining armor. While you’re dispatching enemies, you’re probably looking around for evidence to grab for extra XP. While doing this, you might notice a stash of it held out of reach behind a gate. For some reason, Murphy can’t just rip it off the wall, so you’ll need to find another way.
The visual cue to help you figure out how to open the gate is a group of yellow cable leading away from the side of them. They snake in and out of the wall, but they head toward the room that the arcade owner is in. Once you have him arrested, you’re free to search for the terminal location of the cables.
If you follow them, you’ll be led to a small button on the side of the desk. It’s extremely easy to miss, so if you were just searching the room for loot like normal, you might not notice it. Pressing the button opens the stash, which not only contains a horde of evidence, but the best possible treasure you can find in RoboCop: Rogue City: an OCP Training Disk.
Also, the “No Stone Unturned” achievement.