This is the game that started it all and in terms of the main mechanics is probably still the deepest, most rounded and balanced game not only from the x-com series itself but also from the other attempts to make games in the genre. It has had me coming back every few years since way, way back. Everything is really tied together here - base design affects not only what you can fit in, the bases capabilities and how long it takes to build, but also the layout that you will have to defend if the aliens find it and invade. The terrain you shoot down a UFO over is the (generated) terrain you fight in, the time your troops land affects the light in the battle. Multiple fighters can engage a UFO simultaneously which opens up a lot more strategy, both in how you line them up and how you equip and order them to engage. Likewise downing a tiny UFO with a massive missile is more likely to result only in wreckage, not salvage, but unlike the newest games, blowing some of them up is often a solid outcome as the nations are just happy to see the threats all seen off. Ground combat isn't easy, but with a lot of options in squad setup, equipment and the approach you take, it is often more forgiving than it tends to be portrayed as and the generated terrain and many options create some emergent gameplay which can make it quite interesting. Salvage is also a more important element, with the surviving UFO components and equipment directly relating to what you receive at the end of the mission, which makes for intuitive, implicit sub-objectives. There are of course some niggles, the graphics and sound are ancient but highly atmospheric and some of the conveniences we take for granted in new games aren't there - taking a mix of weapons and having to hand them to the right soldiers at the start of each mission may annoy some and managing base inventories can be tedious for a main base with a lot of salvage. Still, if you like strategy games, you owe it to yourself to play this
