The dark theme acts like the other Google apps with dark themes. It’s not a pure black, which would look great on OLED displays. This is more of a dark grey. The benefit of dark grey over black is less chance of burn-in on OLED displays. The last screenshot shows the new option in the Settings. We love seeing all these app getting dark themes. If an obscure app like Google Play Games is getting a dark theme, that’s good news for more popular apps. Hopefully, someday, Android will have a system-wide toggle for a dark mode.