In my intro to Silent Storm, I mentioned both modding scenes and UFO (used to distinguish the 1994 original X-COM from the 2012 Firaxis one, and not only out of increasingly sad Eurocentric obstinance) without tying the two together. That, it turns out, was stupid, because X-Piratez, a UFO mod in active development by Dioxine, is the best total conversion for any game I've ever played.
Based on OpenXcom Extended, a long-running open source clone of UFO, it takes the story and gameplay structure of the original, and a huge stock of resourcefulness, and turns them into something that's simultaneously very similar and completely new. The result is a dangerously addictive compound of comfortable old UFO with constant surprise, discovery, and content.
The imaginative premise brings together influences from all the X-COM games, as well as smaller touches from spiritual successors like the UFO Aftermath/Afterglow/Aftereight/etc series (principally in its 'after the end' setting and colourful story, the strongest draw of that interesting but flawed trilogy). If anything it fits better than the original story, as a small-time group of ambitious bandits should scrabble for resources a lot more than the combined military elite of the entire planet, something that players of Aftermath or XCOM 2 have likely already observed.
What's that about bandits? Oh yes. Let's talk about the premise.
X-COM failed. The aliens conquered Earth, had their gross tentacly way with it for centuries, and then, at some point, buggered off. Earth is now a forgotten backwater of some stellar empire, awash with mutants, human collaborators, and abandoned underlings of the terrifying, but absentee Star Gods. Your band of all-female mutant pirates has stumbled across an ancient military research base. From here, you decide to make a living cowing the world with acts of theft and violence against the filthy human agents of the Star Gods, extorting protection money from petty local governments and seizing goods, weapons, and captives to ransom from everyone else.
It's bloody brilliant. Your mutants are naturally thick-skinned, stronger and quicker-witted than regular humans, and consequently quite effective in battle even when running at the enemy stark naked, screaming and waving a pipe. So they do. Tool them up with knives, primitive flintlocks and blunderbusses, and a pile of black powder bombs and molotovs made by your "runts", and scout out the local shipping for plunder. Everyone uses ships, not just hostile invaders, so you carry out these raids indiscriminately and incompetently at first. Who are you preying on? Who can you fight? What kind of ship is that, and what kind of resistance and booty can you expect from it?
To begin with, you've no idea. It's perfect thematically because you're a gang of ignorant pirates, and your understanding of the world extends no further than your local area. Goods are bought at extortionate prices from an illegal settlement your people visit. As well as working thematically, the ignorance also works as a gameplay device, leaving you in the dark until you learn, through in-game research and direct experience, what's going on.
You're not required to attack every ship you see, as you're not there to stop a hostile invasion - you're a band of pirates. You only need to hit the ships likely to carry loot you can use or sell, or that threaten your reputation or safety. You can get by with a few great missions in a month and ignore every other target. This is a blessing, as missions can be long and drawn out, and there are times when you dread the appearance of another ship not because you can't handle it but because it's such a hassle doing another mission when you just want to get that research finished or a workshop built.
But that's true of every UFO game, to be fair, and X-Piratez gives you much more room to breathe. While protection funds are useful, the bulk of your income comes from plunder and manufacture. It's also where tangible resources like fuel, ammunition, and metal come from, because, again, you are a band of pirates.
All the unknowns give you an incentive to research. There are heaps of things to discover. The simple pistol/rifle/heavy, ballistic/laser/plasma weapon table is gone, and in its place are countless conventional guns, alien weapons, and derivatives of both to buy, steal, and/or research. Other technology (including a wide variety of outfits offering loads of tactical options) piles up too, and hostages can be interrogated in order to learn about the world.
You can maybe use that unfamiliar rifle if you get hold of it, but you won't know how to reproduce its ammunition without having your "brainers" study it or through interrogation of an expert, which might also lead to conceptual breakthroughs. There's a much slower arms race than in traditional X-COMs and their variants; you won't find 90% of your gear quickly becoming obsolete, as weak enemies never truly go away, hard times pass if you stay alive, and a juicy under-staffed cargo float or passenger ferry might come along next.
It all feels satisfying, as your incentive to improve is based on your increasing ambition, not on a brutal Sisyphean treadmill. You can't powergame your way through, as you're rediscovering science and industry from base principles, not rushing to end-game superweapons. Even with foreknowledge of the game, the logistics of your operation make truly advanced technology (already scarce as the Star Gods control access) untouchable until everything else is in place. Those ancient Roman steam engines were just a novelty without the tools and infrastructure available today, and a similar principle applies here.
You can't reproduce your single laboratory, and even with massive investment can't accommodate more than about 15 brainers. This, again, fits the setting - you're pig-ignorant savages in a ruined Earth, not SETI - and works well with the endless options, as you're pursuing your own ends, not trying to uncover the one way that works. When you can't have more than a few researchers, hiring and directing them becomes less opaque.
In UFO it was never clear whether you should have 50 scientists, or 180, or 410, but here you make do with the few you can accommodate and don't worry about it. Meanwhile, under-expanding isn't a kiss of death because escalation is less drastic and even starter ships have a global reach. Building bases becomes a matter of convenience and preference, not the frustrating demand of protecting the world with radar that can barely reach across the street.
I'm pretty sure it's impossible for one playthrough to cover everything - I'm over a year into a game and there's no end in sight, but still tonnes left to see and do. Playing it requires a different mindset to that of any X-COM game. It's simultaneously harder and more forgiving, with many dangerous foes and no easy countermeasures, but less of a "kill or be killed" situation. On top of that, more strategies and tactics are viable thanks to the sheer variety of stuff.
X-Piratez gives plenty of possibilities but forces you to choose between multiple right answers. Your decisions matter, and feed back into the story and your place in it. Due to concentrating on other things, it was months before I learned how to manufacture basic ammunition, so I'd relied on massed explosives, fire, and a pick and mix of captured guns. My lack of superweapons had me tearing my hair out over a series of disastrous fights with a bulletproof faction that shrugged off my "everyone gets a molotov to the face" policy (being set ablaze is guaranteed to panic most humans, which my researchers tell me is accurate with cold, haunted eyes), but I found ways to fight back and have fun, and learned that stealing a few guns and retreating can be a victory.
You're pretty much destined to be a plucky guerilla underdog against well-equipped foes, so like UFO of old, your blood will run cold when you first see something new and clearly not human (I panicked and immediately began a retreat at my first encounter, such is the reputation of the Star Gods). By contrast, I keep a stash of muskets for a bit of sport when I come across the most pathetic prey. They're quite lethal against unarmoured humans, and there's something satisfying about using a primitive smoothbore, clubbing any survivors with it, then taking a swig of soothing rum from the bottle in your holster. Did I mention that you're a band of pirates?
The base UFO structure is still there, but adjusted and turned to other ends. Terror missions, where aliens once attacked cities to scare governments into surrender, are replaced with mutant pogroms, where various forces victimise your fellow mutants. You're not required to attend, but are asked for help by the Mutant Alliance, a major vector of your reputation, upon which rests your long-term survival.
The interface is improved with shortcuts and tooltips, but still very much that of the original, and parts, like the disassembly/manufacture menus, creak under the weight of options. Some of its presentation... well, I sigh wearily at the blimp-titted anime sex doll rubbish that accompanies some research screens, but its tone is benign, self-aware and never serious, so it's easy to shrug off (to specify, I don't have a problem with the option to send pirates into battle naked. "Screaming naked berserker" is a completely justifiable concept. I just wish they had less silly pubes). The many new graphical assets are coherent and broadly great, and it certainly has personality, something all too lacking in many strategy games.
X-Piratez isn't only the greatest total conversion mod I've ever played; it's fighting a fierce and convincing campaign to become the best UFO/X-COM game ever. If I have one real complaint, it's that I can never again play it for the first time.
X-Piratez is free, but requires files from either UFO or Terror From The Deep, which can be purchased on Steam here. It is still in development but fully functional, and currently on version 0.98A, which is available on the OpenXcom forums here.