X-Com: UFO Defense (1993)

You are in control of X-COM: an organization formed by the world's governments to fight the ever-increasing alien menace.

Command deadly close-combat battles
Shooting down UFOs is just the beginning: you must then lead a squad of heavily-armed soldiers across different terrains as they investigate the UFO crash site. Tackle the aliens with automatic rifles, rocket launchers, and even tanks in the struggle to retrieve useful technology, weapons or life forms.
Research and manufacture alien technologies
Successful ground assault missions will allow X-COM scientists to analyze alien items. Each new breakthrough brings you a little closer to understanding the technology and culture of the alien races. Once you have sufficient research data on the UFO's superior weapons and crafts, you'll be able to manufacture weapons of equal capability.
Develop a strategy to save the Earth
You must make every crucial decision as you combat the powerful alien forces. But you'll also need to watch the world political situation: governments may be forced into secret pacts with the aliens and then begin to reduce X-COM funding.

MINIMUM System Requirements
Windows: XP / Vista / 7 / 8 / 10
Processor: 1.4 GHz
Memory: 512MB RAM
Graphics: 3D graphics card compatible with DirectX 9.0
Mouse, Keyboard.