I am going to place a thumbs up here for Medieval. This is actually the only RPG I have really participated in all year that I haven't played previously. I know this game is not new to the year of 2005 but I found it just in time to get started before the year ended. I have thus far enjoyed getting started as well as reading the previously played scenarios left here by others. I am so excited about really getting into the real depth of playing here.
Just recently got back into AD&D 3.5 and have to say the GM/DM have made this campaign simply amazing. The trials and progression/regression and role play I have not seen since my early child years. The campaign is called the crimson eclipse and is 13 chapters long and we are not close to 1/2 done yet. So in short AD&D 3.5 and its flexibility is amazing if you have a creative group.