Yesterday, special ranked tables were added to the Hearts card game. Ranked tables were intended to be exceptional in having strict rules: no robots allowed, and registered players only. Penalties were applied to those who left a game early.
Some players found that the "no robots allowed" policy was making it impossible to finish their games. After someone dropped out (deliberately or accidentally), they'd be stuck waiting for a long time before the game could continue. This was true even though human players are allowed to substitute at ranked tables... so such tables do show up in the "list of tables" (they don't show as ranked once a player leaves because you do not get ranked if you join such a table after it starts). Apparently, tables where "no robots" applies are especially unappealing to Hearts players.
People are not dropping out from ranked games very often, so that's good. Even so, when it happens, it leaves people waiting indefinitely for fear of losing in the rankings, which is no fun. To correct this, I've now changed the rule so that bots may replace a human who left the table. This is only permitted after the game starts. And in case it is not obvious, winning or losing to a bot does not count towards your ranking!
It is still necessary to get 4 humans together to start a ranked game... currently this involves a wait. It appears that most people prefer to start a game with bots. For those who want to play a Hearts game with humans from start to finish, ranked tables are the best way to go. I hope the wait time will lessen as more people discover rankings.
For those who are curious, a description of how "Elo ratings" are computed is given at the site.