2.1. Arcade style

Although arcade games had their heydey in the 80's, they are nonetheless very popular. Nothing will ever replace walking into a dark, crowded and noisy arcade gallery, popping a quarter into your favorite machine and playing an old fashioned game of Space Invaders. Arcade style games attempt to simulate the arcade games themselves. There is such a vast number of these things that it's nearly impossible to enumerate them all, but they include clones of Asteroids, Space Invaders, Pac-Man, Missile Command and Galaxian.

2.2. Card, logic and board games

Computer based card games simulate a card game like poker or solitaire. The program can simulate your opponent(s).

Logic games usually simulate some well known logic puzzle like Master Mind or the game where you have put sliding numbered tiles in order inside a box.

Computer based board games simulate some kind of board game you'd play on a table top with friends, like monopoly, Mille Bourne, chess or checkers. The program can simulate your opponent.

2.3. Text Adventure (aka Interactive Fiction)

Once upon a time, when Apple ][, Commodore, and Atari ruled the world, text adventures were the game of choice of `intelligent folk'. You are given a scenario and can interact with the world you're placed in:

    You are in a room.  It is pitch dark and you're likely to be eaten by a grue.
    > Light lantern with match.
    You light the lantern.  This room appears to be a kitchen.  There's a table with a
    book in the center.  You also see an oven, refrigerator and a door leading east.
    > Open the oven.
    In the oven you see a brown paper bag.
    > Take the bag.  Open the bag.  Close the oven.
    Inside the bag is a some garlic and a cheese sandwich.  The oven door is now closed.
			

Back then, text adventures were self contained executables on a disk or casette. These days there's usually a data file and an interpreter. The interpreter reads data files and provides the gaming interface. The data files are the actual game itself, similar to the relationship between first person shooters (Section 2.7) and wad files.

The first adventure game was Adventure (actually “ADVENT”, written on a PDP-1 in 1972). You can play Adventure yourself (actually, a descendent); it comes with “bsd games” on most Linux distros. Text adventures became popularized by Scott Adams (Section 11.5) and reached their height of popularity in the late 80's with Infocom (Section 11.4) which are also playable under Linux.

As computer graphics became easier and more powerful, text adventures gave rise to graphic adventures. The death of commercial interactive fiction more or less coincided with the bankruptcy of Infocom.

2.4. Graphical Adventures

Graphical adventures are, at heart, text adventures on steroids. The degree to which they use graphics varies widely. Back in the 80's, they were little more than text adventures which showed a screen of static graphics. When you picked up an item, the background would be redrawn without the item appearing. The canonical example would be the so-called `Hi-Res Adventures' like The Wizard And The Princess. Later on, the sophisticated graphical adventures had your character roaming around the screen, and you could even use a mouse, but the interface remained purely text.

Next there are the `point and click adventures' which basically have no text interface at all, and often have dynamic graphics, like a cat wandering around the room while you're deciding what to do next. In these games, you point at an object (say, a book) and can choose from a pull-down list of functions. Kind of like object oriented adventuring. :) There aren't many graphical adventures written natively for Linux. The only one I can think of is Hopkins FBI (which happens to be my favorite game for Linux).

2.5. Simulation (aka Sims)

Simulations strive to immerse the player behind the controls of something they normally wouldn't have access to. This could be something real like a fighter jet or something imaginary like a mechanized warrior combat unit. In either case, sims strive for realism.

Some sims have little or no strategy. They simply put you in a cockpit to give you the thrill of piloting a plane. Some are considerably complex, and there's often a fine line between sims and strats (Section 2.6). A good example would be Heavy Gear III or Flight Gear. These days sims and strats are nearly indistinguishable, but a long time ago, sims were real time while strats were turn based. This is awkward for modern day use, since a game like Warcraft which everyone knows as a strat, would be a sim by definition.

2.6. Strategy (aka Strats)

Strategy games have their roots in old Avalon type board games like Panzer Leader and old war strategy games published by SSI. Generally, they simulate some kind of scenario. The scenario can be peaceful, like running a successful city (SimCity), or not, like illegal drug selling operation (DrugWars) or an all-out war strategy game like Myth II. The types of games usually take a long time to complete and require a lot of brainpower.

Strats can be further divided into two classes: real time and turn based. Real time strats are based on the concept of you-snooze-you-lose. For example, you're managing a city and a fire erupts somewhere. The more time it takes for you mobilize the fire fighters, the more damage the fire does. Turn based strats are more like chess---the computer takes a turn and then the player takes a turn.

2.7. First Person Shooter (aka FPS)

What light through yonder window breaks? It must be the flash of the double barreled shotgun! We have a long and twisted history with FPS games which started when id Software open sourced code for Doom. The code base has forked and merged numerous times. Other previously closed engines opened up, many engines are playable via emulators, many commercial FPS games were released for Linux and there are quite a number of FPS engines which started life as open source projects. Although you may not be able to play your favorite FPS under Linux (Half-Life plays great under winex) Linux definitely has no deficiency here!

First person shooters are characterized by two things. First, you pretty much blow up everything you see. Second, the action takes place in first person. That is, through the eyes of the character who's doing all the shooting. You may even see your hands or weapon at the bottom of the screen. They can be set in fantasy (Hexen), science fiction (Quake II), present day `real world' (Soldier Of Fortune) and many other settings.

Like text adventures, FPS fit the engine/datafile format. The engine refers to the actual game itself (Doom, Quake, Heretic2) and plays out the maps and bad guys outlined by the datafile (doom2.wad, pak0.pak, etc). Many FPS games allow people to write their own non-commercial datafile. There are hundreds, even thousands of non-commercial Doom datafiles that you can download for free off the net. Often, companies release their engines to the open source community so we can hack and improve them. However, the original data files are kept proprietary. To this day, you still have to purchase doom.wad.

2.8. Side Scrollers

Side scrollers are similar to FPS but you view your character as a 2D figure who runs around various screens shooting at things or performing tasks. Examples would be Abuse for Linux and the original Duke Nukem. They don't necessarily have to be violent, like xscavenger, a clone of the old 8-bit game Lode Runner.

2.9. Third Person Shooters

Similar to FPS, but you view your character in third person and in 3D. On modern third person shooters you can usually do some really kick-butt maneuvers like Jackie Chan style back flips and side rolls. The canonical example would be Tomb Raider. On the Linux platform, we have Heretic 2 and Heavy Metal FAKK2.

2.10. Role Playing Game (aka RPG)

Anyone who has played games like Dungeons & Dragons or Call of Cthulhu knows exactly what an RPG is. You play a character, sometimes more than one, characterized by traits (eg strength, dexterity), skills (eg explosives, basket weaving, mechanics) and properties (levels, cash). As you play, the character becomes more powerful and the game adjusts itself accordingly, so instead of fighting orcs, at high levels you start fighting black dragons. The rewards increase correspondingly. At low levels you might get some gold pieces as a reward for winning a battle. At high levels, you might get a magic sword or a kick-butt assault rifle.

RPG's generally have a quest with a well defined ending. In nethack you need to retrieve the amulet of Yendor for your god. In Ultima II, you destroy the evil sorceress Minax. At some point, your character becomes powerful enough that you can `go for it' and try to complete the quest.

While the insanely popular Ultima series, written by Richard Garriot (aka Lord British) for Origin, was not the first RPG, it popularized and propelled the RPG genre into mainstream. Ultima I was released in 1987 and was the game that launched 9 (depending on how you want to count them) very popular sequels, finishing with Ultima IX: Ascension. You can play Ultima VII under Linux with Exult (Section 11.7).

The canonical RPG on Linux is Rogue (the ncurses library started life as a screen handling routine for Rogue!) and it has infinite variants like Zangband and Nethack (which has many variants itself). Some RPG's are quite complicated and great feats of programming. There seems to be a deficiency of commercial RPGs for Linux. Not counting the rogue variants, there's also a deficiency of open source RPGs too.