The senate, choosing the part and selecting the form of government in the empire are all novelties, compared to the prequel. However, this system isn't of the foremost importance (albeit it is important). You will only need to come here if you want to see certain laws introduced or when the majority supports an ideology, but the ruling party is of a different ideology.
Consist of representatives (1) (the units of the population in favor of the given party) and senators, i.e. the members of the leading party (2). The heroes that support the given ideology are party leaders. Every government has a certain number of senators that influences the number of Leading Parties. A dictatorship allows only one party; a democracy has three senators. Underneath the symbol of the current government you cab see the bonuses provided by it (3). Each form of government provides different bonuses and abilities of influencing your population during elections. Access to new forms of government is gained after unlocking the Xeno Anthropology technology, available in the 3rd stage of Empire Development. If you manage to do that, you will be able to select, in the senate screen, Change Government (4). Changing the government usually requires 50 Happiness points for the whole empire as well as an amount of influence. A period of anarchy will begin, during which all laws will bu suspended, which is the perfect opportunity for unhappy factions to mutiny. Also remember, that populations is systems get a happiness bonus if the party they're in favor of is the leading one (and a happiness penalty otherwise).
Types of government:
- Democracy. Up to three parties are allowed. One more law can be introduced, and and additional happiness per citizen is awarded. A good solution for a vast empire with many citizens. Thanks to the multiplicity of parties, you're able to be more flexible and to introduce different combinations of Laws.
- Republic. It's a bipartisan system. Laws give better bonuses - most of the time, around 5 percentage points more than in other cases (15% instead of 10%). On top of that, you can manipulate the outcome of elections, to some degree, by spending Dust.
- Federation. Similarly, only two parties in the government. You can have two systems more before receiving a penalty to happiness. You can spend influence to manipulate the outcome of elections.
- Dictatorship. A single party in the government. This allows it to gain experience quicker. The systems are much quicker to mutiny, though - it's enough for happiness to drop below 30% instead of the regular 10%. Only to Laws allowed. You can upgrade a system so that your government is propagated there.
There are six ideologies and as many parties in the game. If you have a hero that favors the given ideology, they will become the face of this party. Every subsequent hero from the same party will contest with the current leader. The more often you side with the given party, the faster it's "experience bar" will fill up. Thanks to that, you can introduce more meaningful Laws. Additionally, every hero gains in time access to abilities that are only activated if he's a senator (i.e. when the party he's in is in the government). These abilities should be developed, but only in the case of those heroes, who take part in politics.
These are additional bonuses for the whole empire. Every party has a set of laws, which are automatically activated as they become the leading party (the small symbol of a pin on the party's emblem). If there are more parties in the government, the one that has reaped the most votes is the one that introduces its laws. These laws cost nothing, but cannot be canceled. Depending on the government and scientific progress, you may be able to introduce additional laws. Just click the Pass Laws button. Before you will appear all the laws that can currently be introduced. Some laws are related to specific ideologies and they cost an amount of influence. However, these are usually more powerful and yield better bonuses. In order to unlock these better laws, the given party must be elected often. With every election won you should get access to better laws. The laws that have a white icon instead of the ideology emblem are accessible for everyone.
The elections are held every 20 turns. A couple of turns prior, you will get a preliminary survey of support in your systems. You can also investigate every single system. Some types of governments allow improving your party's standing before the elections, or weakening the opposition. Bear in mind that those actions don't always have to yield the desired outcome. Don't be surprised if a party that supposedly was to win will actually lose with a technically less popular rival - although they will still make it into the senate. Losing the elections doesn't necessarily mean things will go to hell form thence on, or that the game has ended. The only consequence is that you won't be able to use the laws that you used before, and that the leader of the party will no longer support you with their bonuses.