I think it was this game that really sparked my love and interest for turn-based strategy in the first place, and I think most gamers in their late twenties or early thirties would agree that it is one of the best strategy games ever made. Its prototype, Laser Squad 2, was picked up by Mircroprose Software and published in 1993 as UFO: Enemy Unknown (in Europe).
In repelling the extraterrestrial threat, the player is tasked with managing the base and the troops, as well as looking after the funding and research development. The action elements of the game comes into place when you order units to intercept the UFOs, and then sending units to investigate the crash site, neutralize the survivors and salvage the alien technology. I discussed this game with a friend the other day, and the alien autopsies came up. Seems we both agree they were much more fascinating than the 3D illustrations/renderings of today. The level of authenticity and detail of the pictures are really impressive, meaning one could study them for a long time. Truth is you couldn't wait to bring the next specimen to the slab. Morbid, but true.
One of the most important aspects in making UFO a classic was the line-of-sight system. The fact that you could only see what your soldiers were able to see kept the game interesting. During the enemy phase, you can hear movement or even catch a glimpse of your alien foes, plotting against you. The depth of gameplay was well ahead of its time, with research and funding needing constant supervision and combat and character customization central to the strategy element. Hands down one of the best games ever, it had several successors, none of them better than the original.
Click here to download the game. It should run on Windows, et al. No promises.