experiment

Without knowing what kind of game you are plannng, it's rather difficult to discuss mechanics. It's sort of like choosing the cake's icing before you've mixed the batter.

There are always the "standard" paths to victory:

Total Domination (Military Victory)
Most Wealth (Economic Victory)
Subordination (Diplomatic Victory)
Interdependence (Cooperative Victory)

Because it is so easy to define terms for victory, I usually start out with a single goal. Then, during playtesting, we may discover more avenues that may be considered worthy of becoming a goal.

If you still want to try working from the viewpoint of having multiple goals, at least incorporate some "Rubicon Conditions" into your design.

I made up this term to describe critical paths in your game where a player commits to one course of action - for better or worse.

Here is an example:

I want to make a game involving galactic conquest. Since I already know I want multiple goals for victory, let me call them Domination, Quest, Siege and Interdependence (D, Q, S, I)

D requires that a player controls 75% of the galaxy and 50% of the space lanes.

Q requires that a player explore 60% of the galaxy and retrieve an artifact.

S requires that a player controls 40% of the galaxy and 90% of the space lanes

I requires that at least two players achieve a stable balance of trade with the remaining players (such that neither is strong enough to overwhelm the other.)

Okay, now I have to make sure that players can't easily switch between the four goals (although it might make sense to allow a player to abandon the Siege path and go all out for Domination). The obvious way to do this is to manipulate the supply and demand of critical resources. So I need to make up some resources: Food, Fuel, Fighters.
Since this is just an abstraction, there is no benefit to creating a micro-economy.
Using the three resources, suppose D needs the most Fighters, with S coming second, but wait, Interdependence might require more Fighters than Siege ...

Once I figure all that out, I have to ensure that the balance between the resources determines the most logical path. Finally, I may end up with a chart like this:

D - sustainable production (per turn): Food 3000, Fuel 2000, Fighters 5000
Q - sustainable production (per turn): Food 500, Fuel 3000, Fighters 200
S - sustainable production (per turn): Food 5000, Fuel 4000, Fighters 2500
I - sustainable production (per turn): Food 1000, Fuel 2000, Fighters 3000

Now, I'm not saying that I have come close to solving the balances in this example, but if there are easy ways to jump between goals, then I know where to look. (Don't forget the additional requirements stated at the beginning.)

The key to the manipulation of supply and demand probably should be based on the number of space lanes that a player controls. Controlling a planet, meteorite or space station has limited value if trade is restricted between them!

I hope all this rambling has given you some ideas.

Mitch

Along the lines of the multiple paths to victory, you could balance it so that no one path will lead to victory by its self. You could need to follow more than one path to achieve victory.

This could be dome by making the total VP (if you use them) for a particular path less than the VP needed for victory. This should dcreate a situation where players must have variety in their strategies to win.

Another way to create deeper strategy is to avoid linear unit dominance (A beats B beats C). A better concept is to have a cylclic relationship (A beats B beats C beats A) or apply this to other choices in the game.

This cyclic relationship between game units/choices will create a dynamic situation where strategy becomes emergent (the tactics are set but the strategy emerges out of it). If you can achieve emergent strategy in the game then you allow for player creativity in strategic choices and open up the potential for strategies.

Chess, I think, does have a cyclic relationship between the pieces (although it is fairly loose) because even a pawn can capture the queen or put the king into checkmate, despite these being the most powerful pieces on the board.

This brings me to another point. It is the situation (board layout) in chess that dictates the acutal power of a piece at a given time, rather than having an absolute power given to the piece by the designer. This flexability of the piece power in chess creates the explosion of stratigic choices.

So if in your game you allowed pieces to change the dominance relationship based on the situation this will also increase the potential for stratigic choice.

As an example: In the battle of Hastings (1066ad), King Harold had infantry, while his enemy (Duke William of Normandy) had both archers and knights. If this battle took place on flat ground then Harold would have been defeated easily, because William's Archers could have skirmished against Harrold's infantry and the knights would have kept breaking up Harold's formations.

However Harold was able to use the situation to change this dominance of troop types by placing his infantry on a ridge. The knights were unable to charge effectively and the archers arrows were not as effective when shooting up hill. Harrold still lost the battle, but his defeat was harder than if he was on flater ground and could have gone either way (but his troops where also exhausted from a forced march).

So, to sum up. To increase the potential for strategy then:
1) Give multiple paths to victory, but make it so that more than one path will needed to achieve it.
2) Create a cyclic domanance/relationship between various tactical choices/units.
3) Allow the players to change the dominance relationships between these choices depending on the situation and have this mostly under the player's control (but not totally).

I hope these tips help.

There are quite a few games where the decision tree narrows towards the end. Indeed, it's not necessarily a bad thing when done right. Zèrtz comes to mind, where the diminishing playing space can make for tense play.

True. I suppose I should have said variable rather than cyclic (as that is closer to what I was meaning), as it is the situation that governs the unit relationships (ie a good player can place a pawn where it is more powerful than a queen of their opponent).

And another thought:

By having each piece have ultimate power (ie can take any other piece) but only restricted by the movement rules of that piece, this creates the highly variable relationships between the pieces. It is the restrictions that are places on the player that confer the nessesary stratigic (and tactical) potential of the game (imagine if you could move any piece an unlimited number of times to anywhere on the board and make as many moves as you like - there would be no game).

Restrictions can, themselves, be a source of stratigic choices.