After playing 2k18, Madden, and Horizon the majority of the evening, I'm thinking my HDR Game Mode is fine, and I need to re-examine my expectations for HDR. I'm thinking it's all about punchier colors and brighter brights, when that's not necessarily the case. I switched back and forth between HDR Vivid and my HDR Game Mode for example, and while Vivid had the punchier colors and brightness, it lacked subtle detail in the overall picture. Everything was just 'pop' if that makes sense. I think Madden also has a poorly implemented HDR mode, and I was using it to compare as I though the field would and surround colors would be a good way to 'test'. I also changed the color gamut from Wide to Normal, which on the LGs, normal *is by default* wide. Pretty happy with the picture now tbh.
Horizon is dope at 4k+HDR.