Expedition PVE Mode

I recommend there be a new type of super "adventure" for end game content called the "expedition." In this PVE mode you settle and fight to conquer an island much in the same fashion as classic The Settlers IV. Keep all the same buildings and building costs except with dramatically reduced build times.

Introduce Ships and shipyards. The primary reason for ships is to initially bring supplies from your home island to the new island. The more ships the more materials you can import at the start of the expedition. Ship combat could be included as a precursor to the main island conquest portion. However, you don't want to import too many resources because you don't get them back at the end of the mission.

Enemy AI builds and competes with you similar to Settlers IV game play.

Add a few defensive structures such as towers, castles, and cannon fortifications which add combat bonuses and automatically dispatch their garrison to intercept enemy generals.

Conquering the expedition either nets you rewards or allows you to have a "colony" which adds a small but permanent boost in resource income. Put a limit on the number of colonies you can have at one time. Also require players to periodically defend their colonies from invading AI. The better the colony the harder to defend.

Total gameplay time required 2-6 hours. This becomes the equivalent of a mmo "raid." Perhaps permit players to pause and re-continue at later time as long as they complete it within a few days time.