Alternity is a setting-generic Science Fiction game originally published by Wizards of the Coast.
The game is designed for GMs to produce any kind of Modern or SF setting, from techno-thriller to cyberpunk to classic space-opera to superhero.
It's even possible to run modern Horror games with this system, such is its versatility.
What you will need ..
The Alternity game, unlike many games currently available, uses a wide range of dice, rather than being fixated on a single die type.
To play Alternity, you will need the Alternity Player's Handbook & Gamemaster Guide.
There are other accessories available, but these core rulebooks are all you really need.
You will also need the following types of dice: d4, d6, d8, d12 & d20 (the most commonly used).
You can find these types of dice at any hobby games shop.
Other than this, you'll also need pencils, scratch paper & a writing pad (lined would be best).
You may also need squared and/or hex-printed paper (you can get squared paper at a decent stationer, and hex paper can be bought from hobby stores).
Alternatively, you could download the Graph Paper Printer program from the following address: http://perso.easynet.fr/~philimar/
I have found this program invaluable.
If you intend to be a player, the best way to get started is to find a local club or group.
Check your local gaming club or hobby shop for notices, or post a message on A.Net's message boards.
When you find a group, get in touch with the GM of the game to find out more about the specifics of his/her game.
Most GMs will have house rules or varying styles, so it's a good idea to know about them beforehand.
The GM and other players will also help you to create a new hero or convert an existing one for the game.
If you want to be a GM, you'll need to put in a little groundwork first.
If you want to run a game in a published setting such as Star Drive or Dark Matter, make sure to acquaint yourself thoroughly with the campaign book before beginning.
There's nothing more embarrassing than being caught flat-footed by a player with better knowledge of the campaign world than you have!
Creating your own campaign world is possibly a GMs most difficult task.
It's also the most rewarding. The Gamemaster Guide has extensive notes and advice for creating one's own setting,
written by experienced GMs. When creating your world, make sure to do a bit of research.
For instance, if your alternate-Earth setting is being invaded by Aztec T'sa (reptilian aliens) from another timeline,
it's a good idea to research both dinosaur evolution and the history of the Aztecs.
Not only will this give you the information you need to make your setting believable,
but interesting little facts may give you ideas you wouldn't have thought of otherwise.
Whether a player or a GM, if you need any advice just post a message on the A.Net boards.
The members here will be only too happy to help you out.
An Overview of the Alternity System
Most games fall into one of two categories, class/level based (like D&D), or skill-based (like GURPS).
Alternity has taken the best of each style. While there are classes for characters (such as Tech Op or Combat Spec),
they are simply rough templates to help players to get a handle on their new creations, rather than a tight strait-jacket to limit character growth.
The skill system is driven by ability scores, so that a hero with high strength will be better at hand-to-hand combat,
while one with high intelligence will be better at programming a computer.
All die-rolls are based on the control die, a d20.
Situation Dice are added to or subtracted from this roll, which is compared to the ability scores, modified by the skill.
To succeed, the roll must equal or undercut the ability score (for instance, Personality if the hero is trying to sweet-talk a customs officer).
Penalties are added to the roll, which makes it harder to equal or undercut the required score, and bonuses are subtracted from the roll.
Bonuses and penalties are expressed as situation dice, which are added or subtracted from the roll of the control die.
For instance, if one is trying to grab a rope thrown from a ship in heavy seas, the GM may rule that the hero must roll against Dexterity with a +3 step penalty,
to account for the difficulty of the task. In this case, the hero would have to roll a d20 (the control die),
and add d8 to the roll (the situation die).
Beating the required score spectacularly will result in a better than hoped-for success, while failing the roll miserably will result in a disastrous botch-up.
This elegant and intuitive system is the basic mechanic of the entire game, and covers everything the heroes may wish to do,
from researching a library for an obscure but vital bit of information,
to bribing a security guard to blasting their way out of a gunfight.