I would want to ave a complete event system in Sins Diplomacy.

Events can happen based on

gametime
time elapsed
economic/military/reasearch/diplomatic strenght (or change in rank)
Researching parts
discovery of planets
allegiance change
contact with another race
market changes (boom, depression)
Rebellion

using probability variable

Events can trigger:

Fleets
Attack fleets - attacking a specific player or everyone till dead
Strive fleets - fleets travelling through the galaxy from a to b (eg. East to west), attacking everyone on their path 
Invading fleets - A AI player enters the galaxy with a specified fleet trying to conquer as many planets as possible

Market changes
Black market boom
Black market depression
Metal or Crystal Mining income modiefied by factor x for period y
Trading with other player(s) impossible due to <enter reason>

Empire
Contact to fleet lost due to <enter reason> e.g. Magnetic storm (for period y)
Planet income modified by factor x for period y
Modul <random choosen> malfunctions (for period y)
Ship x cannot use abilities for period y
Rebelling planets formed a new empire
Population growth modified by factor x for period y (babyboom, pandemic, supernova nearby, ...)
Diplomatic contact to player x impossible for period y
Phaselanes to system x became unstable - random phaselane speed modifier activ for period y
 

and any other event one could think of. Highly modable of course.