Sounds like you're looking to make a game with the same sort of functionality that Sunrider Liberation Day works where you've got a couple different layers to it, a turn based strategy layer laid out in a grid or hex or whatnot with it's own set of sprites, and a story vn side of things with ways to interact with the characters and such. Could be a lot of fun. Not sure you'll actually need to worry too much about making game overs fun, knowing you, they'll make us laugh. Just for the love of all that's holy please don't put in any missions with escort and protect the defenseless useless npc missions.