Before Xeno Ethics is researched, most random events will be in the form of ethical decisions, often upon initially colonizing a planet. The chosen response will nudge the alignment slider according to the decision made as well as provide some bonus or penalty (or both). Typically, good decisions involve forfeiting a bonus and often a financial cost to prevent future occurrences, while evil decisions usually grant a bonus or money but often at the expense of the local population. Once Xeno Ethics is researched, these events will cease, and the player is forced to choose an alignment. While you may choose an alignment opposite to your trend of respondes to the ethical events, the financial cost may be quite high.
Other random events throughout the game involve phenomena that may temporarily increase the economy, research, influence, or population growth of civilizations, introduce a new minor race on a previously uninhabitable planet, make pirates appear, or result in a forced declaration of war between two civilizations. These events appear to be global, affecting all civilizations in the game.