I've come up with the idea of a massive project that has some sweet RP potential.
The map you would embark on must have a water source, such as a brook or river. Or, for extra challenge, make the water source an aquifer. Or both.
First, you send an embark team with seven picks, all seven dwarves miners, and using the rest of the points *only* for food and drink.
Then, have the dwarves work to dig out a massive fortress complex, build the buildings you want, but don't do anything to specifically encourage immigration, trade, sieges, thieves, etc.
No decorating (smoothing, engraving, statues, etc.).
Once the entire fortress is dug out, or when food and drink is about to run out, route your water source to flood the entire fortress. Bonus points if you can manage to drown all seven of your dwarves in the process.
Whether or not you manage to kill all of your dwarves, abandon.
Reclaim the site, and don't allow your reclaim forces to dig out a new fortress. Instead, have them set up some sort of pump operation to drain the top level of the currently existing fortress. Have them settle within that, and rig a system to drain each successive level when you can.
Thus, you can pretend that your dwarves settled in a massive, flooded cave system, using an elaborate pump system to clear the flooded levels, one by one.
BONUS POINTS: Make it so that if the pump system is ever interrupted, the entire fortress will flood over again. AKA keep the water input going, don't block it off, and label the lowest level as off-limits or something.