Once you reach 120 (full exp. Some say 121) on a bridge operator you will be added on the next weekly maintenance.

And if you get bored of HOF, do damage "accidentally" your teamate in normal room and you will get out of HOF. If you understand what I mean.

Question?  does your score stop when you reach HoF or keep building.  And if it dosent go up after you enter wouldent it be best to lvl every nation to the max before entering or just keep deleting BOs before they hit if you are a one nation player