I remarked in a recent post that I thought Space Empires 4 was the last game to unite a deep strategic game with an equally deep tactical game. As I'm still playing and loving the game more than a decade since it was released, and as I haven't found any 4X game released since to really match it, I thought I might offer you fine folks something of a review. As Elemental, and GalCiv before it, are 4X titles, you might find it relevant. And, hell, it's 2:30 AM and I'm suffering from another bout of insomnia.
Briefly, Space Empires IV (or SE4) is a traditional turn-based (optionally simultaneous-turn-based) space 4X game released back in 2000. Like all 4X games, you control an interstellar race of beings who expand out from their homeworld to colonize other worlds and seek galactic domination. Along the way, you'll explore the galaxy via warp points (wormholes), encounter, spy on, and combat other would-be empires, and research new technologies. It really stands out among the genre, though, due to an unparalleled level of customization and depth. The 2D graphics may turn some people off, but they have held up really well, and far better than 3D graphics tend to. All-in-all, SE4 is just as playable today as it was 12 years ago.
Let's start with the strategic game. The game's depth begins with game creation, where you have all the genre mainstays such map shape and size, and random event frequency, to unique options such as finite resources (which forces players to continually expand or face stagnation) or limited warp points (which results in breaking the map into isolated regions, not immediately accessible without specific technologies). You also have the option to lock specific technology trees, should you find you simply don't like playing with them.
Creating your race is where the customization really takes off. Though the race customization shares a lot in common with other games (you have a pool of points which you allocate towards various bonuses), the scope of customization goes far beyond what you've seen before. You have control over every aspect of your race, from their homeworld's type and atmosphere (Which dictates which planets can be immediately colonized), to their background culture, special traits, unique technology trees, war wariness, and so on right down to altering--percent by percent!--everything from environmental tolerance and reproduction rates, to physical strength and bonus (or penalty) maintenance rates. Additionally, your custom race gains experience that carries over from one game to the next.
Research, as a mechanic, is fairly standard, with research buildings generating research points which are spent with new technologies to unlock new or improved ship types, weapons, buildings, and more advanced areas of research. There are dozens of trees encompassing hundreds of individual tech levels. These technologies range from the mundane (armour, shields, weapons, etc) to truly exotic, like various stellar manipulations (create or destroy entire planets, warp points, Dyson Spheres) that allow you to reshape the map itself. To further spice things up, you can unlock unique trees at character creation such as organic technologies (living armour, cloning), psychic technologies (mind control, better training) and so on, or discover powerful hidden technologies in alien ruins.
Running similar to research is intelligence. Intelligence buildings generate points, which can be spent to undertake covert missions to sabotage enemy ships, cause unrest, steal technologies, and other fairly standard actions.
The strategic map is fairly conventional in some ways, but with unusual depth. The game maps are fairly standard in that they feature a number of solar systems connected together via wormholes to form a galaxy. Where it differs, though, is that each solar system is laid out in a grid, rather than abstracted (such as in MoO games). To engage in combat, ships need to enter the same tile, allowing faster and more agile fleets to avoid enemies, even while within the same system. Additional, systems often contain anomalies such as nebulae and stellar storms, which effect ships located within them. Some might hide ships from scanners, others might make shields inoperable.
A weak point in SE4, compared to many other 4X games, is that planets don't have unique features as seen in MoO or Endless Space. They do, however, vary quite a bit in size, type (rock, ice, or gas giant), atmosphere (none, oxygen, methane, and so on), and resource values. Initially, your race is limited in the planets it may colonize. If you're race's homeworld is an methane gas giant, they can colonize other methane gas giants to their full extent, and other gas giants to a lesser degree (as all those domes your people have to live under, in order not to die agonizingly by asphyxiation, take up a lot of room!). Researching the right technologies allows you to spread out onto rocky and icy planets, but in order to fully utilize planets of a different atmosphere requires you to either capture members of another race or make use of some late-game techs.
The economy of SE4 differs from other 4X games. In most, you basically have two key resources, money (credits), and production. Generally, ships and the like cost production to build (with more production speeding the process, and larger ships costing more production), and having an associated maintenance cost in credits. SE4, however, doesn't make use of credits. Instead, there are 3 resources: minerals, organics, and radioactives. Every component of a ship has an associated cost in one or more of these resources, and the combination of these gives you the cost of the ship. Carefully managing these three resources is key to maintaining a strong economy, as running out of any of them can halt production. If, for instance, your race builds a lot of living, regenerating, ships, you would burn through a lot of organics, and would want to colonize planets with a high organic rating, build more farms, or research more efficient organic extraction techs.
Diplomacy is full-featured, is entirely routine. You can enter into the usual treaties and pacts, exchange maps, ship designs, technologies, etc.
The AI could be better (and indeed, there are some AI mods out there), but even at the default settings, it can be a good challenge for newer players. Like any AI, though, an experienced player will start to see its patterns and spot the weak spots ripe for exploitation. Uniquely, though, the AI is entirely modular, meaning you can have the AI run any or all parts of your empire, right down to controlling specific classes of ships (I usually leave it up to the AI to distribute my population via transports).
SE4's tactical depth begins with designing your ships, a process in which you have complete control. Like MoO, you don't have specific hard-points to fill, and your only limitation is the maximum weight each hull can carry. Unlike MoO, though, you can unlock scores and scores of modules, most of which have dozens of increasingly powerful versions. Looking just at armour, you have regular armour, regenerating armour, cloaking armour, armour that hides your design from your opponents, armour that makes you harder to hit, and armour that boosts shields when it takes damage. Weapons can also be oversized, giving you the option between having a handful of normal Meson Beams, or just a couple extra large ones. You can mix and match any way you want, creating ships as specialized or generalized as you like. Non-combat designs are also possible, and indeed, important. From supply ships and construction ships, to transport ships and remote miners. And the same is true for designing stations, fighters, satellites, mines, drones, weapon platforms, and ground troops.
When designing a ship (or other unit), you also designate it's ship type (useful for having the AI control specific classes), and assign it a tactical strategy, such as "point blank," "board enemies," or "don't get hurt" which dictate how the ship acts when auto-resolving combat.
Combat is turn-based and takes place on a grid. You can auto-resolve combat or control your ships (or even just some of them) manually, maneuvering and firing on enemies. Depending on your ship designs, you will have different options. Besides the standard lasers and missiles, you have weapons which bypass shields, weapons which target only specific modules, weapons which decrease the enemy rate of fire, boarding parties, among others. Even among otherwise standard weapons, you have a wide range of ranges, damage that varies over range, and fire rates. Boarding is an especially powerful option, as you can reverse engineer enemy ships to gain access to new technologies, use the ship yourself, or scrap it for resources. Additionally, many weapons have hard or soft counters. Continuing the look at boarding parties, you could defend against them by installing increasingly advanced security or a self destruct device to destroy the ship if control is lost. Or, you know, just add more weapons to try and destroy any ship before it gets close enough to board.
A unique feature of SE4 is the combat simulator. With it, you can test up to 10 opposing fleets comprised of any of your designs or known enemy designs to see who would likely win. Wondering how viable a hugely shielded but minimally armed battleship would perform against one of the enemies missile heavy cruisers? Or whether a fleet of your ships is likely to overcome another race's homeworld, complete with stations and satellites? Test it here first! It's an amazing useful tool that lets you test strange concepts in a matter of seconds.
As I said, SE4 has held up extremely well over the years, as the sprites and UI are just as clean and clear as ever. My only gripe is that the resolution is stuck at 1024x768. It's not quite as bad as it sounds, though, as many of the windows within the game will expand to fit the screen. It's also highly and easily moddable, allowing you to alter, remove, or create any module, hull, building, technology you like. And there are a ton of mods out there, from updated AI to a Battlestar Gallactica mod, and custom maps and scenarios. While the community isn't as active or large as it once was, it's still possible to find players for matches (TCP/IP or PBeM) or advice. And, for what it's worth, it's an indy title, with the design and programming, as well as some of the sound effects and music done by one man, Aaron Hall. And as we all know, it's important to support indie titles. You can fin Space Empires 4 Deluxe for 10$ on the major DD platforms, or download a demo from http://www.malfador.com/se4.html.
I should mention that Space Empires 5, though, was a largely a failed departure from the series. It had some great ideas, but implemented them poorly, and should be avoided at all costs.
TL;DR: It's a great classic 4X that still runs on modern machines, look into it, if, you know, it's your sort of thing.