Just giving Immortal techs won't do much to make the setting more difficult. Giving a worker will but on Epic that will be too tempting for worker stealing. Normal games should be fine as long as the saves submitted are by Emp and below players. Players winning consistently on Emperor should at least try Immortal or put their saves as shadows. Changing the game speed to Normal will also make the game more difficult (wars aren't as easy). I think players learn the most by comparing their saves and making games more difficult to adjust to the cookbook setting and better players is not a good idea in my opinion. Tweaking the map can be good to learn a few tactics indeed, but it starts being more of a challenge game than the cookbook. There are a lot of things that can be done but the best way to find out what exactly is to ask the people that will be playing the maps. The cookbook usually gets a lot of first round saves but it drops to 4~5 only after that. Is it time? Difficulty? Interest? Options I'd consider: Normal speed with 50 turns rounds Report and vote dates rather than just vote.