I did enjoy Dominic Cook's game diary, but realise that it wasn't designed for those not yet playing Austerlitz and as such didn't really convey the game's atmosphere and appeal.
Austerlitz is a wonderful game, prize-winning in its original German form and licensed across the world. It is administered in the UK with fine courtesy and efficiency by Sam McMillan at Supersonic Games, who has GMed about 250 Austerlitz games.
It is a game of medium complexity, but takes a lifetime to master. Almost.
Each game begins in January 1808 with 16 various powers. Each has its own qualities broadly equivalent to its historical type. For instance the UK is industrially the most advanced, has the best navy, and a great colonial position, but is unable to place troops safely on the European mainland unless a firm ally is first found. The most vulnerable is the Confederation of the Rhine, blessed with a modern competitive army, but limited by the smallest population, and cursed with six ambitious neighbours.
Each turn you receive reports on your economy, army, navy, and trading activities, as well as three pages of maps covering the world showing economic developments, conquests, some fleet sightings, and secret reports from your spies. Every game is different and the answer to every decision is "Depends": upon your best-guesses of what your 15 rivals are doing.
The first few turns (a "game month" every fortnight) are spent building up the economy, recruiting and training troops, jockeying for colonial possessions, and assessing the other players. Before long more or less public alliances are formed and wars begin. Some players are very aggressive; others defensively hope to grow while nobody notices too much. Some are always on the phone; others keep even their names secret, fuelling Gamers' Paranoia. But historically families tended to obtain more than one throne; just look at the Bonapartes, Habsburgs, FitzTancreds.
When enemy forces each totalling at least 100 battalions meet, detailed Simulated Battles are fought. Maps are provided complete with contours, varying terrain types, and computer-generated 'strategic points', as well as lists of the units present with details as to their troop-types, training-levels, and headcounts. Then each player assesses the situation and considers many more changeable characteristics including the relative strengths, speeds, and attributes of units present; the likelihood of reinforcements reaching the scene; the terrain; and estimates of the relative abilities and impulses of the two opposing commanders at handling the particular mixes of troops present. Accordingly, each player makes a plan and issues orders (sometimes conditional) to his units as to tactics, timings, and directions, trying to make sure he has the right blend of artillery, pioneers, cuirassiers, hussars, grenadiers, voltigeures, tuaregs, or whatever, at the decisive point to win the battle, or perhaps merely to suffer fewer losses. Then the clockwork is released and hundreds of phases of observation, movement, targeting, firing, combat, routing, and rallying, are calculated for each of the units present, and summarised on some 30 pages of report added to your regular turn.
These battles are always different, but also change as the game progresses and military inflation occurs. At first only the cheaper troop types are usually worth recruiting, unless a player gambles on making enough early conquests to pay for dearer ones. Later on better and better troops can be raised, meaning that any battle in 1819 will be very different from one in 1809.
Another realistic element is that victory is only obtained by concession, not by any victory point system. This is pure Clauswitz: your war aim is to persuade your enemy to give in. So defeat in the field, loss of a capital city, or of your national granaries, are only decisive if your enemy accepts it is such.
Up to three players can be agreed as winners. The fastest games so far have ended in 1811; most are finished by the end of 1814; but one or two have reached the 1820s. So if you join an Austerlitz game, be prepared to invest between two and seven years of real time before the game concludes.
Most players find it so addictive that they play in several games simultaneously.
Austerlitz is a great, subtle, always surprising game, wonderful if you like it. I do; whatever else the postman brings I always open an Austerlitz envelope first.