An open source reimplementation of the original XCom
OpenXcom is an open-source clone of the original UFO: Enemy Unknown (X-Com: UFO Defense in USA), licensed under the GPL and written in C++ / SDL.
The goal of the project is to bring back the tried and true feel of the original with none of the issues. All the same graphics, sound and gameplay with a brand new codebase written from scratch.
User is required to have original gamedata (possible to obtain from e.g. Steam) installed to ~/.local/share/openxcom/data/