Freeciv

Freeciv is a free and open source turn-based strategy game that's openly inspired by the Civilization saga or, more specifically, the second and third installments of the franchise. Players can play both offline against the artificial intelligence in games that can last for hours, or online against more than 100 human players from all over the world.

The gameplay in Freeciv is very similar to that of the aforementioned Civilization 2, although with some additions and tweaks inspired by the third installment, as well. New games start in 4000 BC by default, with just one settler and one explorer; it's up to you to guide your civilization through the years, centuries, and millennia on your quest to become a dominant world power that's capable of winning the game. But how do you win the game? That's easy: you can either annihilate the rest of the civilizations or build a spaceship to reach Alpha Centauri.

The learning curve for the vast majority of 4X (the strategy subgenre to which Freeciv belongs) is usually quite high. For this reason, the game not only has a good tutorial, in which you can learn the basics of the game, but it also has a Wiki with several official manuals depending on the rules you're playing with. That said, anyone who has ever played a Civilization game can see that the game is indeed very similar, and the general mechanics are almost identical to any game in Sid Meier's franchise.

One of the most notable aspects of Freeciv is the large number of customization options available when creating a new game. On one hand, there are the scenarios, which are games created by the community in which you play on certain maps (Japan, United States, Europe, Earth) with a specific number of opponents. On the other hand, there are also the standard games, in which you play on a procedurally generated map against however many opponents you want. The best part? No matter what, you can play both against the AI and against your friends over the Internet.

Freeciv is an excellent turn-based strategy game and a true love letter to video games. The first version of this project was released completely free of charge in 1997, with many improvements made to it since then, including bringing it to more than a dozen operating systems in more than 30 languages. It's a real gift for video game fans and, more specifically, anyone who appreciates a good strategy game.