The OpenXcom Engine

SupSuper’s open-source reimplementation of the original XCOM game engine, OpenXcom, is nearly complete! Check out the code at Some notes for reading:

  • There’s a simple build process with few external dependencies (just SDL and YAML).
  • Several “make”-like systems are implemented in parallel. You can compare and contrast how CMake/autotools/XCode/MSVC look for the same code.
  • The engine is somewhat modularized:
    • “Basescape” for the base management GUI
    • “Geoscape” for the world map
    • “Battlescape” for tactical combat
  • However, the headers aren’t organized clearly and there are some cross-includes between the different modules.
  • Game data like item/tech states are parsed from YAML and accessed by a “Ruleset” library.
  • The “Savegame” system is misleadingly named; it’s actually the container for all persistent player state.
  • There are beautifully concise (1-page) implementations of A* and Dijkstra’s algorithm in Pathfinding.cpp
  • Cringe at memory-management horrors like:
Craft::~Craft() {
  for (std::vector<CraftWeapon*>::iterator i = _weapons.begin(); i != _weapons.end(); ++i) {
      delete *i;
  delete _items;
  for (std::vector<Vehicle*>::iterator i = _vehicles.begin(); i != _vehicles.end(); ++i) {
    delete *i;

(which translates to zero lines of code in modern RAAI C++)

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