Phoenix is a game of space conquest and diplomacy, with an initial period of expansion and technological and economic growth. Each player controls an empire, which starts from a single homeworld and expands outward by conquering worlds. The goal is to own more than 55% of the worlds in your galaxy, either singly or, in games where several empires can share victory, jointly with other large empires or your declared diplomatic partners.
The game map is 2-dimensional, wrapping around on all edges (mathematically, a torus). Homeworlds are scattered fairly uniformly across the map, with each homeworld separated from its immediate neighbors by about 12-16 parsecs. It is not uncommon for one or two large areas without a homeworld to exist in any given galaxy, so empires are not guaranteed an immediate neighbor in all directions.
Empires expand by loading armies aboard fleets and jumping them to nearby worlds. If a world is empty (unowned), a fleet can simply unload its army, conquering that world at the end of the turn. If the world is owned, either by another player or by one of five computer-generated neutral races, you must either convince that player to gift it to you (the neutrals will never do this) or you must take it by force -- by successfully invading that world to get your army to the ground and then defeating any defending armies.
Fleets jump only to worlds, never to empty space. Each fleet may make only one jump per turn and the distance traveled must be less than or equal to its empire's jump range. A further limitation is that certain orders -- the jump and combat orders, including invasions -- require a command post on the ground, within command range of the fleet or army performing the action, to issue the order. Starting jump and command ranges range from 4-7 parsecs, less than the distance separating player homeworlds. Thus, empires must expand for at least a few turns before they can attack each other.
Each empire also has a ground and space combat proficiency. These two proficiencies modify the effects of the attack and defense values of land units and spaceships during ground and space combat respectively. These proficiencies and the ranges discussed above are each based on an underlying technology and increase during the game as that technology improves. A fifth technology, general science, governs an empire's research points, which it allocates each turn to improve its technologies, including general science itself. Doing the last defers improving an empire's other technologies (and hence its ranges and combat proficiencies) to generate more research points to allocate on future turns. Technological development in Phoenix consists of managing this trade-off, as well as deciding which of the four other technologies to improve and in what order.
Each empire is one of seven races. Not all races need be present in every game; indeed, all players may choose to be the same race. Each race specializes in one or more technologies, gaining increased chances of improving them through research as well as bonuses to the proficiencies or ranges based on them. In addition, each race has different starting forces and may build units not available to other races. Beyond this, there are no "special rules" for any race.
Each empire starts with a small number of military units. Additional ones may be purchased by expending production units (PUs). PUs are generated each turn by mining planets to produce raw materials (RMs) which are then converted by industrial complexes into PUs. World extraction values (EX) limit how much mining may be done each turn and range from 4 to 30 (except homeworlds, which have 40 EX). Military unit prices range from 2-300 PUs. PUs can't be transferred between worlds. To produce the more costly military units an empire must either save its PUs for many turns (generally inefficient) or else centralize its production, shuttling RMs generated on outlying worlds to its homeworld where they can be converted into PUs by industrial complexes built there. A further incentive to do this is that the most expensive military units are spaceships, which must be built at a 'starport' of size at least equal to their PU cost. Each increase in starport size costs one PU; thus only a few large starports tend to be built, usually at homeworlds in order to use them efficiently.
Empty worlds have no mining or industrial facilities. To use their EX, it is necessary to bring modules (a type of land unit) and convert them into the needed complexes. Doing so costs more than building such complexes directly; thus you must trade off bringing a small number of modules to cheaply "bootstrap" an empty's production versus bringing lots of them to quickly make full use of the empty's EX. Neutral worlds generally have some mining and industrial complexes on them but must be conquered. This requires military units, some of which may be lost in combat.
Another demand on an empire's limited economic resources is the need to build command posts, another type of land unit. As mentioned above, command posts are needed for each jump and combat order. They may only issue one such order each turn. Thus, having more command posts lets an empire take more actions. However, command posts are fairly expensive. The trade-offs between building command posts (to take more actions), military units (to conquer more worlds), modules (to speed development of empties) and homeworld resources (to eventually build bigger, more powerful military units) are central to economic development in Phoenix and must be carefully managed.
As empires expand and begin to encounter each other, the major diplomatic issue will be drawing borders to define spheres of influence (avoiding early conflict in order to concentrate on development). However, as empires finish developing their easily taken nearby worlds and their technological capabilities improve, attacking other players' worlds will become more attractive. The most effective attacks -- balancing further reductions in military risk and the time spent defeating your foe versus not getting a big enough share of the spoils -- seem to involve two or three empires ganging up on one empire. Diplomacy is therefore important not only to avoid being attacked but also to line up profitable attack options for your empire.
Military matters will loom in importance as you shift towards a war footing. There are many different units available, ways to arrange them into armies and fleets, and military tactics possible in Phoenix. Some units, such as drop troops, allow invading armies to bypass defending fleets by only having to survive one round of fleet combat before getting to the ground (instead of having to clear space of all defending fleets to land as armies must normally do). Certain space units, drop-stoppers, prevent this. Some space units are fighters, which provide cheap firepower but require transports to carry them (and are lost if their transports are destroyed). Static units are also cheap but may not be moved and thus are useful only on defense. The many different jump and attack orders can be used to achieve different effects. Fleets and armies can sometimes be split up or combined during a turn, which can also affect combat. Skillful use of these options and tactics will often spell the difference between defeat and victory. In addition, players can declare blockades during an attack (to interfere with the defender's RM shuttles); contest worlds they are unable to take (to disrupt the defender's production while awaiting reinforcements); and raze system resources, either as a last-ditch defense (to deny the victors spoils of war) or as an offensive tactic (razing a starport to hamper a defender's mobility by doubling his cost to build additional space forces).
Empires coordinating military actions may find it useful to declare an 'alliance'. This allows them to avoid accidentally shooting each other's units during combat and to shuttle RMs to and unload onto each other's worlds. Alliances allow only limited cooperation between empires -- in particular, an empire may not load its armies onto its ally's fleets. Alliances are formed by mutual agreement but may be dissolved by either party at the start of a turn.
In games with more than seven players, several empires can win together (up to one-quarter of the empires in the game). By default, the largest empires controlling more than 55% of the galaxy will win together. However, this can be modified by forming factions. Factions win or lose as a unit, using their combined planet total to determine their size for victory purposes. If you've been successful militarily, negotiating your way into the winning faction -- or ensuring diplomatically that the other large empires are willing to win with you - is often the key to victory. Factions, unlike alliances, are binding; they may be modified only by mutual agreement (which provides another use for them, as diplomatic surety).
Finally, Phoenix is a game of limited information. The map is not known at the start of the game. Fleets may only jump to worlds which that empire has scanned. Detailed force reports are only received for worlds you own or where you have units. Race choices and homeworld locations are not published by the game program. The only information besides your own empire data you receive each turn is a planet tally for all empires (or factions) sorted by size and this list does not identify which empire has which total. (It is provided to give you a basis for judging how well your empire is doing compared to other empires generally.) During the game, players must decide what information to trade, whom to trade it with and when to trade. Commonly traded information includes approximate homeworld locations (useful when drawing borders and sizing up potential allies); racial choice (when planning joint attacks); planet counts (when trying to determine who are the leaders) and faction status (to figure out who is in a declared faction). Traded data either comes from players (who may falsify or omit some data) or, in the case of program generated information such as scan reports or turn forecasts, may be sent directly from the program itself (however, all data transmissions from the program are logged so that other players checking a turn's log will know this information has changed hands).
Phoenix is a space conquest game that begins with a period of initial expansion. Throughout the game, players must manage their technological and economic development as well as deciding what information to trade and with whom to ally. During the midgame, empires shift to a war footing and work together to eliminate other empires, thus continuing their growth. In the endgame, empires race to control more than 55% of the galaxy and, in games where several empires can share victory, to form diplomatic agreements -- sometimes by explicitly declaring factions -- to win together.