Im not sure Empire is running any bonuses right now. Even the sign up bonus may be gone. I was reading on BW yesterday and someone was complaining about it. I would check before depositing. Hopefully I am wrong.

edit: I hope its not wrong to post this link here, but if it is someone let me know and I'll remove it or one of the admins can. This is the link at BW talking about Empire. Check it out before depositing there, I may be misreading it.
http://www.bonuswhores.com/phpBB2/viewtopic.php?t=19628