Chocolate DOOM..................
Nate Drake adds a touch of chocolate to your Raspberry Pi through installing a version of the ground-breaking first person shooter
Nate Drake isn’t gorging himself into a diabetic coma on chocolate, he’s blasting his heart out on his favourite SBPC and the best ‘90s shooter.
Despite the clichéd plot and clunky graphics, id Software’s Doom has enjoyed huge popularity since it exploded on to PCs in 1993. It helped cement the first person shooter (FPS) genre of video games, and spawned a number of sequels, spin-off games and fan‑made levels.
Even those who are too young to remember when Doom was initially released will likely be familiar with the FPS genre. Because Doom is the most iconic FPS of them all, it’s important to recreate the original ’90s experience as closely as possible and for this reason we’ve selected the Chocolate Doom Engine to run on your Raspberry Pi.
This project assumes that you have a Raspberry Pi 2 or 3, running the latest version of Raspbian. Use the commands sudo apt-get update then sudo apt-get upgrade to be sure of this. If you want to play Doom’s multiplayer deathmatch mode, you’ll also need your Pi to be connected to your home network and/or the internet.
Getting the Lowdoom
Being an FPS means that all the action is experienced as if you’re looking through the eyes of the main character. The basic premise of the original game is that you must explore the moons of Phobos, Deimos and then Hell itself. Playing a space marine who’s able to wield a decent selection of weaponry, you have to fight your way through demonspawn, possessed personnel and the forces of darkness [the usual commute to work then–Ed] to have any hope of winning.
The satanic imagery and ultra-violence weren’t welcomed by several religious groups and political pressure groups, who campaigned in vain to either censor Doom or make it more family friendly after its release. Germany banned the game out of hand for containing “bloody, sadistic violence”, although this ban was repealed in 2011.
However, there appears to be no such thing as bad publicity. Doom sold 1.1 million copies between 1993 and 1999, making it the eighth best-selling game of that time. By 1995 there were an estimated 10 million PCs globally with a version of Doom installed.
Gameplay is simple in theory, if not in practice. On each level you must locate the exit to the next area. Helpfully, these are marked with an exit sign. However, you have to make your way through a maze of levels, identical corridors and locked doors. Some help is available in the form of power-ups, which have been liberally scattered around the place by persons unknown. These include key cards, armour, weaponry and first aid kits. You can also make use of the in-game map by hitting the Tab key to see where you have been.
The many monsters that populate the game have an irritating habit of showing up when least expected. They also guard valuable items and exits and have an unfortunate tendency to shoot at you or throw fireballs from a distance.
Although Hell has numbers on its side, the enemy AI isn’t particularly advanced and they can also be goaded into attacking each other if one gets in another’s way.
Another advantage is the arsenal of in-game weapons. Although you begin with a pistol, as the game progresses you can lay your hands on shotguns, chain-guns, plasma rifles and even the unholy BFG (Big Fragging Gun) 9000.
Start your Engine
It helps to think of the Doom engine as being the executable parts of the game, as opposed to the WAD files ( see Where’s all the Data, opposite) that contain raw data like graphics, sound, weapons and so on. The engine handles aspects of the game such as the overall structure of levels and movement.
The official Doom engine that was developed by id is known as Vanilla, because of its relatively bland flavour. Doom enthusiasts refer to Vanilla Doom to distinguish between the official game engine for running Doom and any variants. The distinction is important because the Doom engine was modified and reused in several commercial games, such as Heretic and Hexen.
Since id released the source code of the Doom engine in 1997, a number of community developers have also adapted it to their purposes. Chocolate Doom is one such project.
Despite being a rejig of the game engine, Chocolate Doom aims to reproduce the experience of playing the original version of Doom as much as possible. Any modifications to the original game engine don’t interfere with the authentic gaming experience. More importantly, Chocolate Doom strives to be compatible with all Doom Expansion files (WADs) that were designed to work with Vanilla Doom.
The only area where Chocolate Doom differs significantly from the original is when playing in the multi-player deathmatch mode. One player’s machine has to act as a server, unlike in Vanilla Doom where players would connect directly to each other. Fortunately this is very easy to set up ( seeDoomDeathmatches,overleaf).
Where’s all the Data?
To play Doom you’ll need both the engine and the WAD (Where’s All the Data) files. WAD files contain game data such as details of levels, graphics, sound effects and background music. The idea behind WADs is to make it easy for people to make custom levels and modifications for the game. WADS exist separately from game engines such as Chocolate Doom and must be downloaded from elsewhere. There are two main types of WADS. For the purposes of this project we’ll focus on iWADs (short for internal WADs), which contain data for entire levels of the game.
When Doom initially came out, although enthusiasts were keen to start creating new graphics, sound effects and so on, they couldn’t do much to change some of the game’s fundamental values. such as how much damage was dealt by monsters. Since the release of Doom’s source code and some remarkable efforts by the community at large, however, all aspects of the game can now be changed and there are thousands of WADs. Some of these are simply slight alterations to the game itself, whereas others expand hugely on the premise of the original game. One of the best known of these “MegaWADs” is EternalDoom, which contains 32 full levels, each of which is around four times larger than the levels in the original Vanilla Doom.
As impressive as this achievement is, Eternal is simply an expansion of the Doom Universe. Other WADs are considered “total conversions” in that they replace all resources used in the original game. The first of these was Justin Fisher’s AliensTC, which is based on the film franchise.
Those interested in working in the industry shouldn’t consider designing game levels as a waste of time – Fisher was offered employment by game developer DreamWorks, which he declined in order to finish his university degree. However, other designers of popular WADs such as Iikka Keränen did go on to find employment with major video game companies to work on official projects.
For copyright reasons, in this project we’ll focus on the official shareware WAD of Doom ( DOOM1.WAD), downloaded from fan site www.doomworld.com. This contains only the first episode of the game, Knee Deep in the Dead, and was initially released to encourage interest in the game. Upon completion of the first level players were encouraged to order the full version.
This said, there are a number of official and unofficial WADs available for download, so provided it’s legal in your country, feel free to load and experiment with these.
Freedoom isn’t free
The Freedoom Project is an excellent example of the enduring popularity of Doom. The stated aim of the project is to create Doom- style WADs made entirely of free content. Because id Software has released the source code to Doom, the underlying game code is free. Freedoom builds on this with a number of levels, artwork, sound effects and music.