UFO Online: Invasion was a turn-based tactical MMORPG from the Russian studio Bad Pixel, in the spirit of classic X-COM. In its story an alien ship attacked Earth in 2024; humanity fought it off, but the world was changed and alien creatures and bases remained.

Turns were simultaneous: a minute to plan, then every action resolved at once, which let dozens of players join one tactical battle. Characters were built from more than a hundred skills across eleven masteries. The economy was player-driven, with players gathering resources and crafting and selling gear, and clans fought over bases that produced the best equipment.

The game closed on April 1, 2022; the developers cited the international situation and being unable to process payments. No official servers remain.