A real time strategy developed by Stardock Studios, the makers of Galactic Civilizations, "Sins of a Solar Empire" combines the space warfare of Homeworld and the development and management of Civilizations without really committing to either.
In SoaSE, you can play as one of three races: humanity, the psionic Advent, and the technologically advanced Vasari. All three races share the same basic gameplay, though there are some differences in units and technologies. The basic gameplay is based on planets and their gravity well; each planet acts as a "base" of sorts that can be upgraded on the planet itself with infrastructure improvements or reinforced with structures built in orbit like defense platforms and construction facilities. Each planet has a gravity well where ships can move around and engage in combat; traveling between planets causes ships to automatically enter faster-than-light speed once they're out of the planet's gravity well.
There isn't a lot of specific customization you can do on planets (all building construction takes place in orbit), but there are important things you can do on them nonetheless. Improving the infrastructure of the planet increases the amount of taxes that you get from that planet, and also the loyalty of the planet's citizens. It's also possible to explore the planet to look for resources or artifacts hidden on it. The structures that can be built in orbit range from defense platforms to mining outposts to ship construction yards to trade posts to research stations. Defense platforms, like gauss or missile launchers, have a certain radius and are placed around your planet; due to the size of the gravity well around the planet, you have to consider which trade lanes the enemies will come from when placing your platforms. Mining outposts harvest two of the three resources in the game - metal and crystal (the third being credits, gained by taxation) - from asteroids around the planet. Construction yards are your basic unit-building stations, and can build whatever you've researched. Trade posts generate credits depending on how many of your planets are linked up with them. Finally, research stations (either civic or military) affect how much research you can do - the more stations you have, the more advanced your research can get. Research has four types - civilian (affects planets and buildings), military (affects units that can be created and bonuses they receive), fleet (affects experience and maximum amounts of ships), and artifact (grants special bonuses if you receive alien artifacts).
Combat in the game is two-dimensional, and doesn't take advantage of the "space" concept like Homeworld did, which is a major disappointment. Rather than a strategy game, the combat feels more like an assortment of numbers stacking up against each other. Ships can't maneuver particularly well, so in most cases the battle strategy consists of lines of ships shooting at each other. The only real thing you can try to do is maneuver toward your planetary defenses so that they'll be shooting your enemies as well. The only real thing that makes this acceptable is the intended size of battles and the number of battles that can be going on simultaneously once your empire expands. It's easy to keep track of ships due to the sidebar interface that shows all ships (friendly and enemy) near a given planet, and furthermore if you zoom out enough, all the ships show up as icons that allow for easy real-time management. In short, this is a strategy game, but more on an indirect scale of numbers vs numbers, rather than a direct tactical level. The variety of units in the game - from small corvettes to long-range missile frigates to gargantuan dreadnoughts - keeps things interesting, but in the end it all comes down to numbers.
Besides ship-to-ship fighting, the other part of galactic conquest is taking planets. This is done by nuking the planet from orbit with either capital ships or specially-made siege frigates. As missiles fall on the planet, its infrastructure decreases; when it's down fully, it can be captured. Depending on the planet's loyalty to its previous owner, it might be difficult for the new planet to adapt to your empire, and rebellion is entirely possible if the planet's inhabitants are mistreated. The other, more peaceful way of getting new planets is to colonize an uninhabited planet. The colonized planet is generally much more loyal than a conquered planet, though the infrastructure and upgrades start at their base levels.
Diplomacy also plays a key factor in the game; when playing against AI opponents, you will often be given missions that can raise your standing with them, making them more likely to agree to a ceasefire or an alliance. It's also possible to put bounties on the heads of players - rewards and incentives for other players to attack them, essentially. Finally, you can hire pirates to raid certain planets and upset your enemy with no cost in terms of your own ships.
The graphics are decent, but minimal - the details are good, but due to the scale of the game, it's difficult to focus on one specific ship. Furthermore, the animations and movements of ships are minimal - they're basically sitting completely still while little bursts shoot out of their guns. The camera is hard to manage, and the process of zooming in and out often led to my losing track of my units. There's no real parts where you can sit back and just enjoy the cinematic feel of your units blowing up a fleet of enemy ships, even though there is a "cinematic" option that gets rid of a lot of the HUD elements. The sound is not particularly great. The music is decent, but forgettable, and the game's voices are really annoying. Overall, they both kind of detract from the experience in general.
As a whole, this game has a lot of good ideas, but the execution isn't that great. It feels like it's trying to do much, and while it's ahead of a lot of other games in its specific field, it doesn't feel properly committed to any of its gameplay elements. It doesn't have the detail to be a proper management game, and it doesn't have the tactics to be a proper fleet battling game. However, it's a decent effort at a spacefaring conquest game.