This is one I tried a while ago, and hope to play out again.
A government experiment opens up a portal to another world, one ruled by magic, with dragons, mages, warriors, anything from WOW works. The ruler of the connected world manage to keep the portal open from their side, and invade. Technology against magic. We would be pushed further and further, with perhaps more portals opening up on other continents, some would be successfull, and some would be closed. My character would be a Marine Platoon or company commander that is captured by your character.
If this appeals to anyone, let me know.