While I own SR1, I hadn't had much time to play it before SR2 released April 2015--but the reviews were good, the price was right, and I'm glad I went for it. The original SR1 struck me as a typical entry into the sci-fi grand strategy genre, though I'd peg SR2 for pausable, real-time 4x, as the developer states. And with a major overhaul to the research screen and some fixes a month later, and a free DLC/expansion planned for later this year, that developer has been paying close attention to the gem that is SR2.
What I appreciate about SR2 is what I loved about Endless Space, SoSE, Star Drive: it's the sci-fi 4x that we love, but the mechanics are different at a fundamental level. Ironically, although the mechanics themselves appear disparate--spread over 5 "tabs"--I'm not sure I've played a game before SR2 in which the varied win-conditions are so integrated. The "currencies" of the game (money, energy, research, influence, defense) are effective at all stages of play: some technologies can be researched using energy, cash, or influence; artifacts and some ship components require excess energy to activate/build; cash can be used on the diplomacy screen, energy during some diplomatic actions; some combat modules require energy to activate; diplomatic actions allow access to some resources (not currencies; see below), or enable actions that affect currencies; currency, resources, and diplomacy can all facilitate system defense.
While there's never been a 4x game that has expressly recommended that you focus on a narrow-minded strategy for success, SR2 might be the first that mechanistically forbids it. The win conditions in SR2 feel so tightly interwoven that one truly feels one can use any--and must use all--to achieve victory. With the exception of the Advent cultural dominance from SoSE--which took an eternity, it seemed, to accomplish victory--a “diplomatic victory” has never really felt viable/desirable in a game before now. And it’s fast and effective in SR2. Planets of your enemy empire can be invaded by your ships (requiring between 1 and 5 mins), destroyed by artifact “buster” ships (about the same), or annexed via diplomatic vote (ditto). In the very first game I played, I used diplomatic annexations to take over all of the systems/planets of my first opponent; the second declared war on me to try to prevent the same fate! (But you can still annex your opponent’s systems during wartime!)
Let's talk 4x:
-Explore: You have the option to either have all stars' locations revealed (though not their planets), or the opportunity to discover connections one system makes with another. Personally, I prefer the latter...and then I start with a pair of scouts! Go grab those anomalies! All ships in the game have the option to travel in normal space between star systems or galaxies, at a rate based on the ship's design devoted to thrusters. The alternate forms of FTL travel make it faster, at the expense of a currency (FTL points), or requiring a station (e.g. warp gates or fling stations), or the use of energy for a skip drive system. You can also use energy (for telescopes) or influence (for spy actions) to see what your opponents are doing.
-Expand: You can't just expand willy-nilly, or you're going to find your budget eaten up by the cost to maintain level 0 planets--which, by default, do not make enough in taxes to pay for themselves, disregarding any extra structures you may have placed upon them! It costs money to provide the colonists their colony ships, then it costs money to maintain your people on low-level worlds. The higher level worlds more than make up this difference, and clever management can minimize the time between having your colonies work against your budget, and having them work for it. Most structures require some sort of upkeep, so when you're not using those buildings anymore, feel free to scuttle them. However, your populace will slowly "develop" their planets, one tile at a time; structures built upon developed land have lower initial build costs and upkeep requirements. Higher population also develops planets faster, and some planets have moons that can be developed for a high, one-time cost to expand their developed land. Some artifacts can perform a similar function.
While colonization is not necessarily limited by distance, trade between systems (and therefore, the import/export of resources between your planets) requires a trade presence, represented by a "next-system over" border. This can be artificially expanded by certain space stations. Some artifacts, via the expenditure of very high amounts of energy, can create new planets in a particular system, or new stars within your trade border. Why create new planets...?
-Exploit: ...because each planet has (95% of the time) an exportable resource, which can be used to create "pressure" on the planet to which it is traded. My strongest negative criticism of this game is the use of the term "pressure". :P Think of it as "capability": 1 X "pressure" allows a planet the capability to build a one-tile-sized structure that produces some resource/currency related to that pressure--economic pressure creates markets which provide money; energy pressure creates power plants which provide energy; research pressure creates universities which provide research, etc. "Pressure" capacity is capability capacity: a planet with 6 pressure cap can build up to six of these small buildings. Focus all of the pressure on a planet to a single currency, and that planet provides a lot of said currency: six economic pressure can create up to six markets, each providing money. This allows you to focus your civilians on building things that affect desired resources—import labor pressure to a planet to make it a ship-building powerhouse; import economic pressure to all of your level 1+ planets if your budget is bloated because of your rash of colonizations; if a planet has Cylium, import all of your energy-related resources to it to get their cilium-power generation bonus; import your research-related pressures to the planet upon which you’ve established the United Research Center, and be sure your diplomatic strength is sufficient to vote against its re-establishment in another empire’s territory.
Some pressure/resources don't necessarily translate to a currency, though are still vital to your empire: labor is required to create all ships and almost all space stations ("orbitals"); defense allows you to generate free defense ships either all over your empire or focused on a specific set of systems; "happy", "psionic reagents" both help to slow/prevent the militaristic capture of your planets, etc. Some asteroids can also provide resources/pressure, although they must first have labor camps/mines established on them by a planet with labor.
Something pretty cool: your empire only starts with a single planet, labor and cash on that planet, but that's it; all other currencies/resources require you to get out there and find them, or build them on your planets. Will you prioritize research, or influence, or energy generation?
Each planet begins at level 0 when first colonized, and can hold just 1 billion (1B) people--the smallest possible population level that allows one to use a planet. Planets can, via the importation of resources, level up to level 5. Because the amount of resources increase at each level, your empire of 100 planets may be entirely focused on leveling up enough level 1's and 2's in order to level all of your level 3 resources to level 3, and a select handful of planets up to levels 4/5. With increased level comes increased population, and potential access to high-level resources on the planet--and with those come increased income, land development, and pressure capacity. Leveling a planet to level 1 requires food and water, so early in the game you're on the lookout for these resources, and eventually your empire becomes, in-part, a balance between which planets get the water/food resources, and which planets have the land upon which to build hydrogenerators and mega-farms, which provide an innate water/food resource, respectively, though require high amounts of cash to build/maintain. You can require that planets auto-import resources to a particular level, or you can micromanage which planetary/asteroid/artifact/diplomatic resources go to which planet--this is a finesse which I am still learning. ;P
-Exterminate: I've seen a few negative comments on the forums regarding the fleet system in SR2, but I love it; in addition to its functionality, it's yet another small mechanistic change that provides SR2 its unique playstyle. Each fleet is headed by a Flagship--the only kind of ship that can keep care of itself. Your flagships are then provided Support ships--much smaller ships to which you may not directly provide commands, but which can share the propulsion (e.g. FTL) of their flagship. The ship design system allows you to create very small (i.e. cheap) flagships with very large support capability, which would create a sizable fleet that could be disabled if the fragile flagship is destroyed--or, you may create large, expensive flagships with little/no "control" subsystems, which minimizes the size of a behemoth flagship's support fleet. Once a flagship goes down, any remaining support ships effectively become automated: they will join your local support fleets if automated in one of your systems, or will simply float in space until destroyed in an opponent's system. The range of ship design is extensive.
There are three general types of weapon systems (projectile rail guns, missiles, and lasers), with upgraded/expanded versions available in research. Each is generally countered by Armor, although you can research different varieties of armor, each of which is particularly effective at handling a specific weapon style. And I'm still getting a handle on custom ship creation, which basically goes like this: your Hull Size--which you can just type in a freaking box; make it 10000, why don't ya! ;P --determines how much "internal area" you have for subsystems. Want a more effective subsystem: literally devote more internal space to it. Want a lot more: unlock the Titan upgrade, then fill it with engines or it’ll be too bloated to move without gravity engines. The ship design screen is abstract, so the "shape" of your design has little effect on the visual representation of a ship on the map, though it strongly affects the order in which subsystem hexes are destroyed, and if the "core" of a subsystem is destroyed, the subsystem fails until repaired. The ship "AI" will dictate the performance of a particular ship within a fleet; those small flagship carriers I described earlier benefit from large-hulled support ships (say, 20-30) with lots of forward armor that can screen them from incoming fire. This is something I'm still trying to master as well, although my favorite combination thus far is a large carrier flagship (hull 300-600) with lots of forward armor, fleet supply, engines and FTL systems, and *all* of the support ship control I can fit. Then I fill the support fleet with thousands of command worth of large support ships, hull sizes 20-30. Some players don't particularly care for support fleets, though, but it's an easy fix: just don't include any support command in your ship designs. Also, look out for the "create random blueprint for this ship" button; when I first dared to create ships, I pressed this button a lot. Some of the designs it gave me were awful, but it helped me figure out what kinds of systems ships should/could have; then, playing around with adding/removing hexes helped me understand how stats related to hexes in subsystems.
And...more learning. :}
-Diplomacy: why isn't this an "X" in "4x"? As stated above, this might be the first game in which diplomacy feels like a legitimate win-condition, primarily because part of it is mechanized to annex planets/star systems. That's right: if your influence is too low, you may not be able to prevent an opponent from just claiming one of your systems in a vote! But you can do the same, and *this* is why you've been sinking energy into intelligence drone artifacts, claiming leverage action cards, building influence pressure structures, etc. But diplomacy is a fundamental mechanic of the game: you can use influence to purchase certain upgrades in the research tree; some diplomatic actions will allow you to provide free, innate food resources to planets you want to level up; influence can be used to "name" ships, planets, and systems, increasing their effectiveness, or can be used to provide defensive/moral support to planets being invaded/sieged. The "Zeitgeist" actions pop up randomly, and you've got to be prepared with a store of influence and diplomatic action cards to either vote them up or down, giving yourself extra bonuses if you were the most supportive/opposed empire. Votes aren’t free! Use your influence to buy vote cards to play later, for yet more influence. Energy can be used to create limited voting power as well. Some people feel that the diplomacy system isn't "diplomatic" enough; personally, the SR2 devs have given diplomacy a new kind of mechanistic weight such that it *feels* weird, but performs like it actually matters in all stages of the game.
My first couple of games were on 50-60 star maps, because I was afraid my Dell gaming laptop would lag; it did with Star Drive 1, though it's my understanding the new Star Drive is better optimized. Haven't had any lag issues with SR2 thus far, excepting the initial load of a saved game. My fourth game, currently on-going, has nearly 200 star systems (~800 planets) in three galaxies with five AI--no lag, no bugs. It's a well-optimized game. Naturally, I spend most of the game time paused--F9, by the way; not sure if you can rebind that, don't much care. My pause time is spent micromanaging...until I need new ships...or need to plan out research pathways...or I'm doing diplomacy...etc. The game's economy works on 3-minute budget cycles, so it's easy to spend all of your budget in the first 10 seconds of a new round, or to approve too many new projects/colonizations, and watch your next budget plunge into the red over the course of 60 seconds. However, although your budget may end in the red for the next three minutes, you can either take active steps to get it into the black for the next cycle (e.g. scuttle unused ships/orbitals/structures/planets), or wait for your current plans to come to fruition--upkeep is reduced as planets automatically develop more of their land area, income increases as population grows and economic pressure is used to construct markets. Finally, research and diplomacy can both provide current funds and bigger budgets.
I'm looking forward to the expansion later this year, if only because the current system is so integrated that I *had* to become proficient in each aspect in order to achieve victory. The tutorial tells you *how* to play the game: you move the screen like so, order around units and manage resources like so, go to this tab for this function, this other for a different system, etc. But it doesn't explain much of the kinds of strategies you can use to win, perhaps because the strategy is simple: "master all of the mechanics, micromanage for efficiency." In that sense, it is a "medium to learn, difficult to master" game; as stated above, I'm on my fourth game now, 65 planets in three different galaxies, five medium AI opponents, and I'm still learning how to maximize the efficiency of my empire. The game doesn't penalize you for low efficiency...at the lower AI difficulties. But we'd never say no to more options in research, diplomacy, artifacts, etc., all of which I'd be fine with having to research to some extent--the initial options are all plenty to handle, and trying to plan for artificial planetoids and ringworlds are sufficiently end-gamey. OMFG: start early to build the damn artificial planetoids, or you may never import enough ore to build and then upgrade one! :P Optionally, imported ore can be transformed into labor via construction upgrade in the research tree, so mine as much ore as you can if you can afford the miners. And use the "tractor" ships to tow asteroids specific star systems. Did you know that could be done? No? Like I said: difficult to master.
It's a phenomenal game, with layers. Get it, play it, be confused, then learn how things work. At first, it was an intimidating process, but that wanes quickly, helped along by the intuitive, if different, user-interface. Like I said: the lower AI difficulties will challenge you while you learn, and the advanced difficulties will challenge you when you feel like you've "mastered" the game. It's your fault for being so presumptuous. SR2 is a highly stream-lined, optimized, and mechanically inter-dependent system that will test your micromanagement skills without taxing them for the sake of "challenging" you simply by giving you too much to consider. Each stage (early, mid, late) of the game presents its own challenges, and if you haven't kept up with your more-difficult AI, it'll surprise you, though not unfairly (unless you've selected the highest difficulties, you masochist). As far as an indie game/developer goes, SR2 places as highly as any you care to name.