It is November 28th, 1998. UFO activity has increased significantly on earth, and the UNO founds an independent organisation called X-Com (eXtraterrestrial Commando). This organisation is lead by the player to save earth from the threat.
At first, you build a base which will remain your only one for a long time somewhere on the world map in real time. In theory, you can build several ones, but this costs too much money at the beginning. In this base, you can hire fighters, scientists and engineers and also build new sectors within the base. Furthermore, soldiers are equipped with weapons - ranging from handguns to grenades and automated cannons - here, to be ready for the fight against the invaders. It's also possible to build tanks. While you're in a base, time is freezed, so that you're not under time pressure. Only on the scrolling world map, time is constantly running with choosable speed.
Sometimes, you actually get involved in battles. There are different kinds of those; the most common and easiest one is to shoot down a single UFO and then examine to the crashing site. If the UFO has already landed, shooting it down is not necessary anymore, but the battle gets a lot harder in exchange. Once a month, the aliens commit a terror attack on a city. In such a scenario, you have more than one goal: Again, you have to kill all the aliens, but this time, your time is limited: Only if you're quick, you can prevent innocent civilians from being killed. Each dead civilian decreases your score significantly. The most difficult battles are attacks of bases. Either you find an alien base and try to defeat the onslaught of aliens, or they are attacking one of your own bases. Then, it really gets hot: If you lose, the base is lost. If you don't have another one, the game is over.
As soon as the first UFO appears on the radar, the game really begins: It's shot down and a small, at the beginning restricted to 14 people, group is sent to the crashing site to clean up with the last remaining survivors. That's done in turn-based tactical battles: Each fighter has a certain amount of action points (AP) which he can use to duck, run, shoot and reload. When the AP are all spent, the next fighter gets his turn; once all fighters are done, the computer-contolled aliens' turn starts following the same scheme.
The basic structure of the battles are similar to board games like Axis and Allies or Risk. The player can only see what's in his soldiers' view, some turns are therefore only used to find the last remaining enemies. That can be very time-consuming and annoying, especially since the game - in contrast to Jagged Alliance - doesn't switch to real time when there is no foe around. When you've beaten all enemies or if you retreat your team, a summary about the mission is shown which rates your performance in different grades. In addition, you take the alien materials and dead enemies with you. The aliens can also just be stunned.
Of what use is that? Stunned aliens can be studied in a climate cell (if you've built one). The dead bodies are brought to the scientists. There, they're dissected to find out about the weaknesses of the aliens - knowledge which you can take advantage of. The materials are meant for the laboratory where they can be studied, too. After some research, your engineers can replicate items. This way, you get your hands on advanced alien technology, and you can even build your own spaceships for example. Research is one of the most important elemens of the game in fact: I don't know of another game in which studying technology is so much fun. There are just so many different possibilities.
There is only one resource in UFO: money. Money makes the world go 'round, as they say. Soldiers, scientists, research, expanding your base or building a new one, everything swallows huge amounts of this vital resource. Because money doesn't go on trees, you have to work hard to get it. 16 countries are involved in the project, at the beginning, they're paying the sum of 5.999.000$ together which you have to invest intelligently. If you're not successful and lose against the attackers, the affected countries will certainly not increase their payments to your project, but decrease it. And if your performance is really weak, or if a terror attack isn't prevented successfully, you can count on this country quitting altogether; this is the worst thing which can happen. From now on, the aliens can build bases in this country and thus operate more easily. Bases have to be found and destroyed in tough and expensive battles.
The soldiers in your team gain experience raise level gradually in an RPG-like fashion. The player can't influence how they're improving. There are twelve basic abilities for the soldiers, the most important being the amount of action points, the hitpoints and the energy. Each shot and every step uses energy, and if it reaches zero, the soldier can't be used for a couple of turns. In heated situations, this can often be fatal, it's better to five your characters a little rest from time to time. If you're facing several superiour aliens, some soldiers may panic: They're just running and shooting wildly. Some aliens can even take telepathic control over your fighters.
At the end of each month, there is a summary. Again, you're rated in five grades. The better you get away, the higher your chance to get more money; on the other hand, weak performances can cause countries and thus money sources to quit. If you've done badly over a longer period of time, the game will probably be over at the end of the next month.
The mixture of real time strategy and turn-based tactics goes on this way over many years in the game without getting boring. Month after month, you're hoping for good results, are happy about technological advancements and gloat about the various new alien races. This is really the special thing about UFO: It can never get boring for the player, because if you get bored - or if you get too self-secure - and lean back, have one or two bad months, you can pretty much forget about winning the game. Only if you really concentrate and stay careful all the time, you can beat the game. UFO is certainly not easy and above all not a game for beginners. On the other hand, it's not unfair in its difficulty which can be set to five levels.
Graphics and sound are okay, the two-dimensional view always stays easy to grasp and the musical score is limited to the very basics, but it also doesn't get on the player's nerves, but fits the athmosphere.
On the whole, a very recommendable game, but be warned: Completing the mission against the aliens can take weeks. And after that, the next difficulty level awaits you because of the completely non-linear campaign...
An almost completely identical sequel was released a year later under the title "Terror from the Deep" which offered a slightly changed scenario and a halfway-new and amusing story. All the other X-Com games released later (Apocalypse, Interceptor, Enforcer) are only related with the first game through their names, and they're not as recommandable as UFO.
Translated by Mr Creosote