Great comparison. I find Steemit to be very addictive, even wrote about it in my first post, https://steemit.com/introduceyourself/@sjt10369/i-m-a-steemolic .
Even on vacation I've caught myself checking the site several times a day just to see what is happening. The concept of adding sub-games as mentioned by others would be very powerful and just add to the addictive habit that Steemit is becoming for so many.