William Hartston devises the game to end all games - and to decide which ones suit you
Games are traditionally classified into categories such as board games, card games, dice games, race games, war games, role-playing games, murder-mystery games and a dozen or more other categories which provide no more than the most superficial description of what the game is all about. Today, we offer a complete taxonomy of competitive games - a classification system that goes beneath the surface of each game to provide a way to judge whether it meets your requirements.

An analysis of the important factors that really distinguish one game from another reveals five major dimensions that need to be taken into account when deciding whether a particular game suits you. The first concerns the number of participants and, in particular, the number on each side. The real question to ask yourself here is whether you want to shoulder absolute responsibility for the result of the game. Or, to put it another way, do you want someone else to blame when you lose? If you demand all the glory of victory, and are prepared to accept the full ignominy of defeat, you will choose chess or backgammon rather than a partnership game such as bridge, or a board game, such as Trivial Pursuit, that can be played in teams. In general, team games are for the gregarious, individual games for the asocial, and partnership games for the anti-social (with only one co-team member to blame when things go wrong, partnership games are perfectly designed to provoke arguments). The situation is, however, further confused by some of the most popular games, such as Monopoly or Cluedo or Scrabble, which allow several individuals to compete at the same time, rather like athletes running in separate lanes. For the most competitive, this offers the chance to beat a number of opponent all at once, while for the less ambitious it offers a sense of community with one's co-losers. (Hint: when playing Scrabble, always try to sit on the immediate left of a non-competitive, social type. They always try to maximise their own score, irrespective of whether it leave opportunities for the next player to make a killing on a triple word score.)

The second major dimension is the role luck plays in the game. Chance will play its part in any game played with dice (such as backgammon or Monopoly) or played under conditions of incomplete information (bridge or Cluedo) or starting with a shuffle and distribution of the elements of the game in an unequal fashion (almost any card game). In some cases, such as Cluedo and duplicate bridge, the luck element is reduced by placing all players under conditions of equal bemusement, but still some are likely to be favoured by making better guesses than others.

Depending on the degree to which you fancy your luck, you may play backgammon, card games, bingo or the National Lottery. If you feel congenitally unlucky, you may turn to chess, though even there luck plays its part. Indeed, it has been calculated that a complete beginner, playing legal moves at random, has about a one in 10120 chance of defeating the world champion. The most attractive balance is a game that enables us to think how clever we are when we win, but to blame our rotten luck when we lose. There is, as far as I know, only one game of total skill, and that is the game of Snap!

Next, we come to the matter of time. If we start playing at midnight, will the game be over by breakfast? Many of the most popular games of recent years, such as Connect-4, or Articulate or Jenga, are over quite quickly, and everything reset in seconds for another game. They are ideal for those of us with short attention spans who require repeated doses of a competitive thrill. Bridge offers a more sophisticated version of that recipe, with a single hand taking only a few minutes, but a complete rubber having the potential to last considerably longer.

Then there is the important matter of study. If you want to become good at anything - and even if you are not especially competitive, most games are more enjoyable if you play them well - there are two routes: natural talent or hard work. However talented you are, however, some games demand a certain amount of study if you want to get the most out of them. In backgammon or poker, you need to learn the odds and familiarise yourself with standard techniques; in bridge, there are bidding systems to master, and in chess there are libraries of theory on openings and endgames. The older and more established a game becomes, the more difficult it is to survive on talent alone, and the easier it becomes for a diligent hard- worker to acquire all the abilities needed to compete at a high level. This, of course, has become the main problem of Trivial Pursuit: trying to answer puzzling questions on a variety of topics was fun until a breed of yuppie-nerds spoilt it all by learning all the answers.

Trivial Pursuit, however, provides us with the key to the final dimension in our taxonomy of games. We have covered competitiveness, commitment, time and talent, but there is one other factor without which many games would be incomplete: alcohol. The final question to ask of any game is: "Will it be more fun if most of the players are at least mildly intoxicated? Bridge isn't; Poker may seem so at the time, but definitely isn't in the cold morning light of a loser's hangover; chess and backgammon can be; and Monopoly, Cluedo and Trivial Pursuit definitely are improved by an injection of alcohol. So is Snap, for that matter, which shows that even a game of pure talent may be improved if you can introduce a factor that diminishes the skill level.