Okay so hear me out, I think a game mode similar to classical RTS games such as Star Craft or Supreme Commander would be a good fit for this game. Similar to 4x events, this event would drastically lower costs, travel and training time. Units are made in seconds, resources come in more frequently, researching is faster, maybe minutes but costs a good amount of resources. These game modes could easily be finished in hours, days and maybe weeks depending on the players. It would be fast paced, intense and easy. Also this game mode would drastically downgrade upkeep's for all units. Players could create huge naval blockades, hundreds of units, walls of missiles,(Maybe this would be a good time to bring in missile interceptors?) heavily fortified core providence's, the choices would be endless!