During routine sensor scanning of the Stroggos surface, a strong energy emission has been picked up, apparently emanating from a mountain region of the planet previously assumed of scarce strategic value. After scouting the area where the emission was detected, we have discovered a large, fortified complex built into a deep valley surrounded by towering peaks. Data in our possession suggest that the site houses a Reactor similar to the one that empowered the Big Gun in Cerberon. Unfortunately, the device happens to be buried deep under the ground, thus rendering an air strike ineffective. It will be your task to infiltrate this notable example of self-sufficient Strogg settlement, codenamed Citadel, in order to locate and destroy that Reactor. A successful mission will bring another critical blow to the Strogg, and probably remove any chance they have to reorganize their war machine.
First of all, make sure you have patched Quake II to the current, final version 3.20 - Citadel will not work with the retail version of Quake II, so download and install the patch if you haven’t done yet (an unofficial 3.24 patch does exist, and Citadel works fine with it as well). To install and play Citadel follow these steps:
1) Create a new folder named citadel in the Quake II folder (the same folder containing QUAKE2.EXE), and extract all files contained in this ZIP archive into it.
2) Right-click on QUAKE2.EXE and select Create Shortcut. Right-click on the newly created shortcut and select Properties. In the Properties, modify the Target line by adding +set game citadel (with one space before the "+" symbol, this is very important), as in the following example:
"C:\Program Files\Quake2\quake2.exe" +set game citadel
3) Move the shortcut to wherever you want and double-click on it to run Citadel. You will be brought directly to the menu. Start the game and select your favourite skill level as in normal Quake II (or load a saved game).
Note for Knightmare users:
Citadel is fully compatible with the popular custom engine Knightmare. If you have Knightmare installed on your computer, use KMQUAKE2.EXE (instead of QUAKE2.EXE) to create your modified shortcut.