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orbital mechanics game idea

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Joined: 07/20/2009


I've always been interested in space flight, so i am working on a game which mimics some aspects of orbital mechanics. I devised the movement system first and i'm still looking for the game aspect to use with the rules.

Here is the basic movement system:

The gameboard consists of seven concentric rings called „Orbitals“. The first orbital has six (equally spaced) squares, the second eight squares, the third 12, the fourth 16, the fifth 20, the sixth 24 and the seventh 30 squares.

Each square has an upward arrow, connecting it to the closest square in the upper orbital, and a downward arrow, connecting it to the closest square in the lower orbital. Since a neighbouring „upper“ orbital has more squares than its „downward“ neighbour, some neighbouring squares in the same orbital may have downward arrows connecting to the same square in the downward orbital.

Movement of spaceships is only possible along and in the direction of these arrows. Movement between squares of the same orbital is not possible, but this is where gravity comes into play.

Every playing piece on the game map (basically planets, asteroids and spaceships) has an orientation which is either clockwise or counterclockwise. All stellar objects (planets and asteroids) have the same orientation (for the sake of simplicity lets assume clockwise orientation). At the start of each turn, there's a „gravity phase“, where each object on the map (including spaceships) is moved one square in its orientation direction along its orbital. If a ship is to rendezvous with an asteroid on the same orbital, it would shift into a higher or lower orbit, wait one or several turns until the asteroid is in a neighbouring square and then move back to the original orbit.

In order to speed movement a little bit up, planets have a gravitational effect on their neighbouring squares. If a spaceship enters a square which is directly connected to a planet square, the ship can either immediately move onto the planet square (and land), or it could even move one square further with the following limitation: during this double move, the ship may not change it's direction of movement. If it came from a lower orbital, it must move to the higher orbital and vice versa. If it entered the neighbouring square counterclockwise of the planet, it could only move clockwise and vice versa. This kind of movement is called a "slingshot move" in constrast to a "powered move" described above.

Whereas a spaceship can only make a limited number of powered moves a round, the slingshot moves are basically unlimited. If planets are properly aligned, a ship can move quite far without the need for powered moves.

That is the basic movement mechanic. One of the game ideas is „solar taxi“ which i will explain below.

Joined: 07/20/2009
Solar Taxi using orbital mechanics

In solar taxi, each player owns a sleek small spaceship for personal transportation. The solar system is crowded with planets and asteroids, and people need transportation between the celestial bodys.

There are seven planet playing pieces numbered 1A to 7A and 6 asteroids numbered 4B, 5B, 6B, 6C, 7B and 7C. The number denotes the orbital the playing pice is placed in, the letter is for identification. The playing pieces are placed equally spaced on the respective orbitals. There's a marker for each celestial body (marked with the number/letter code), these markers are placed in a cup. Each player selects a spaceship and places it on a planet of his choice.

The gravity gun. This is a gimmick to make spacecraft movement more interesting. If a player moves his taxi in a neighbouring square of another taxi, he may exchange the position of both taxis by firing the gravity gun. The defending player may chose to let the attack succeed, or try to evade. If he tries to evade, both players roll dice. If the defender rolls higher, the shot misses and each taxi stays where it is.

Turn sequence:
gravity phase – all playing pieces on the map move one square in their orientation.
Passenger phase – a yet-to-define number of passengers is generated. For each passenger, two markers are drawn from the cup. The first marker is the starting location of the passenger, the second marker is the destination the passenger wants to go. Passenger markers along with a marker for their destination are placed on the starting point on the map.
Movement phase – players move their ships in clockwise order. A space taxi has one free powered move per round and may burn up to three fuel points for extra moves. A space taxi can hold a maximum of six fuel units. The fuel tank can be refilled at any planet if the player passes a turn there. A taxi can hold two passengers. A taxi needs to land on a celestial body to pick up or drop a passenger and therefore ends the movement phase for that player. Once a passenger is dropped off at his destination, the player is awarded with victory points. The scoring scheme is far from perfect at the moment, I simply calculate the difference between the start and the destination orbital.
After 20 rounds of play, a die is rolled at the beginning of every round. If a one shows up, the game ends and the player with the highest victory point count wins.

Since the game map changes every turn, the challenge in this game is to predict where advantageous constellations of passengers / planets or asteroids will appear in future turns and to position one's taxi accordingly. A trip taking lots of turns to complete might turn into a short trip a few rounds later.

I'm still working on a better scoring method and an endgame condition. On my map, there's an elliptical slice of a „comet“ orbital which crosses the circular orbitals of the planets and asteroids. The comet could be triggered by drawing cards and destroy asteroids or shift their orbits. Some playing cards may add randomness to the game. This is still work in progress and suggestions or comments are welcome. In a later stage, I want to use the movement mechanics for an asteroid mining game with an economic dimension as well.

Joined: 07/27/2008

I've been working on a similar design (less detailed than yours):

- First orbit has 6 spaces, 2nd has 12, 3rd has 18, nth has n*6. Orbits n and n+1 are connected in 6 places.
- Each planet has:
- A direction (clockwise or anticlockwise).
- X movement points (1,2 or 3).

So in the gravity phase (yes, there is a gravity phase too) each planet moves X spaces in its direction. As there are 8-10 planets the gravity phase is fast and not boring at all.

In this design, the ships can move freely without suffering the effects of gravity, but as they must accelerate and decelerate, longer trips cost more energy than shorter ones (proportionaly)


Travel distance Energy
1 1
2 3
3 6

(triangular numbers)

Good luck! :-D


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