OpenXcom Extended

OpenXcom Extended is a modern adaptation of X-COM, the legendary game that started the whole series. Many fans are convinced that the first part of the series is the most successful of all. It has very nice graphics (even without discounts for age) and amazing gameplay.
The game supports the installation of mods that make it more interesting: with new maps, types of weapons, combat units and much more.
If you haven't played X-COM, you have a great opportunity to do it now.