The first one is probably the most interesting. Hack and Slash type games can get repetitive though, so if that part is bad, it makes half of the game boring or monotonous to play. As for two and three, meh. Civil war warfare doesn't sound exciting and can't really say much on the medieval fps one. So here are a few of mine that have been trolling around in my head for awhile. 1. This is more of an abstract idea at the moment, but here it goes. So usually in games, deaths and other misdeeds happen without any real consequence. So I was thinking what if in addition to the usual punishment for these misdeeds, there are also moral punishments, maybe guilt, your victims being on your mind throughout the game, and other ways where your past actions make an appearance in the game. 2. So you are some regular looking Joe in some fantasy world. Without telling you (the player) a lot of the story, the player figures out they must kill some bad looking dudes, raid dungeons, acquire something, etc. But then at the end of the game, YOU WERE THE BAD GUY ALL ALONG!!! 3. Elderscrolls meets the Sims. You live a life in some real-world location, and I'm talking a fucking huge location, without any goal besides "do what you want to do". Maybe you can pursue a career, become an art thief, be homeless, whatever.