OpenXcom: OpenXcom (clone of the UFO: Enemy Unknown) OpenXcom: OpenXcom: OpenXcom is an open-source clone of the original OpenXcom: UFO: Enemy Unknown (X-Com: UFO Defense in USA), OpenXcom: licensed under the GPL and written in C++ / SDL. OpenXcom: OpenXcom: Homepage: https://openxcom.org OpenXcom: OpenXcom: OpenXcom: OpenXcom: