Descent - The Game
Most people using D2X-XL will know perfectly what Descent is about and how to play it, but for the few new to it I have written a brief guide to the game to you give an idea of what you're up to when entering a PTMC mine on a far far away planet in the dark of outer space.
Descent pits you in a battle in underground mines infested with robots whos AI has been messed up by a hostile computer virus. You are a mercenary pilot named 'Materiel Defender' who is sent by the PTMC (Post Terran Mining Corp.), the owner of the mines, to get rid of these robots, and possibly the source of the virus. You are equipped with a small space ship, the Pyro GX, and a basic complement of weapons, which you can upgrade throughout game.
As Descent 1/2 are rather old games, all you have to do is to shoot everything that moves (apart from the Guidebot), and pick up everything that floats around (weapons and other stuff). Eventually you will find up to three color coded keys allowing you to access locked areas of the level. Don't forget to pick up the hostages that are kept prisoners somewhere in the levels, as saving them will award you extra points.
To finish a level, destroy the reactor hidden somewhere in it and fly through the exit before the mine blows up. Instead of a reactor, you will encounter an especially big, tough and mean boss robot every once in while. It is a good idea to save the big missiles for these encounters.
Descent is a mixture between a regular 1st person shooter and a flight sim. Just think of a groundpounder with strafing along the vertical axis added, and allowing you to roll along the ship's longitudinal axis. You will need to practise for a while to be able to control the ship and keep your orientation, as often there is no real up and down, or floor and ceiling. In the beginning, enabling 'auto leveling' may be helpful, as it aligns your ship along the nearest plane. Once you are more skilled, this feature is rather a hindrance though.
Descent offers several cockpit views. Toggle through them with the F3 key. All of them display your remaining shields and energy and currently selected primary and secondary weapons. You can display several types of auxiliary views using the Alt+F2 and Alt+F3 keys (rear view, guidebot view, map view).
To replenish your shields, pick up the blue orbs destroyed robots leave behind. To fill up your energy, pick up the yellow energy sparks or find a fuel center (usually these have golden sparks twinkling inside them).
Various powerups will help you in the game: You can find invulnerability powerups, cloaking devices, head lights, and ammo racks allowing you to carry more ammunition. The original Descent has no inventory, so invulnerabilities and cloaking devices were activated when you pick them up and work for a while. You will often find them in an area where you really need them, so make sure to check out the situation and pick them up when things are getting hot. With D2X-XL, you can enable an inventory, allowing you to store cloaks and invulnerabilities for later use.
There are two basic types of weapons in Descent. Primary weapons are comprised of guns, which come in two varieties: Those firing energy (laser, plasma, etc.), and those firing kinetic projectiles (the good ole bullets). Secondary weapons are comprised of missiles and mines.
Descent 1/2 offer a map view in the form of a 3D wireframe to help you orienting in the often maze-like levels. You will need some practise to be able to interpret it though. Special areas like energy centers are colored in the map. Gaps in the walls displayed in the automap often are hints to hidden doors and secret areas.
A great help particularly in complex levels can be markers that can be dropped from your ship and given a short text message. These markers will show up in the map view, too.
Some levels contain teleports (a floating red appearance) that lead to entire secret levels. Usually these levels rather contain puzzles you need to solve to gain access to all the goodies contained there, than a lot of robots to fight. You can enter and leave secret levels several times, as long as you don't destroy their reactor. It is not possible to save in a secret level, so it may be a good idea to collect some stuff, return from the secret level and make a save game, before entering it again to gather more stuff.
There are two kinds of triggers in Descent: Invisible 'fly through' triggers that are activated when you pass the area of a level where they are located, and visible control panels on walls, which you have to shoot to activate them. Often access to parts of the level is only granted when finding and shooting the right trigger, turning off force fields or unlocking locked doors.
Descent 1 and 2 offer a great variety of robots. Most of them have ranged attacks using guns and/or missiles. Some have melee attacks, tearing you to pieces with huge claws of tempered steel or sucking all energy out of your ship. Some bots drop mines and flee when you approach them. Other bots have no or only weak weapons but alert all other robots nearby. Some robots kamikaze you and explode when they hit you, doing considerable damage.
Sometimes you will meet a gigantic boss robot that has extremely powerful weapons and can teleport inside the level, so might suddenly appear behind you, or escape from you if you really manage to corner it. Some boss robots can only be destroyed using energy weapons, others only with kinetic weapons and missiles. Listen for the sound when the boss receives a hit: If you hear a metallic "crash clank" instead of an explosion's booming, it is immune against the type of weapon you are using against it.
Descent 2 (and 3) gives you a little helper: The Guidebot. He is locked away somewhere in the mine (usually near your entry point). It can guide you to powerups, keys, robots and the reactor or boss robot. Again, for skilled players he's rather a nuisance.
Certain areas of a level will produce new robots when you pass them. You can identify them by the network of purple veins covering them. Flying through invisible triggers placed somewhere in the level will activate them. Unless you are playing on 'insane', they will stop production after having been activated for a couple of times.
Pressing F1 in-game will open a window displaying the most important shortcut keys.
Pressing F2 in-game will open the configuration menu. Regard that with the new menu style (blueish, transparent menu background) the game will continue to run while you're in the menu. Press the pause key (Ctrl+P) to pause the game in-menu.
How to set up or join a multiplayer game is described in detail in the multiplayer how-to, so I will simply list the available multiplayer game modes here. Most game modes are also available as team games, pitting one team against the other.