VP distribution

I think that depends on how you distribute them to the players. For example, in Dominion, you have access to different VP cards which you must buy. So players have to time when they want to concentrate on VP, and equally hope they pull enough money on their turn to buy the VP card they want.

The strongest incentive would be to just score ABC sets, maybe adding in a secondary bonus or two as Ryan suggested.

You could do 1 for A, B, or C... +1 for AB, AC, or BC... +1 for ABC

So a set of ABC would be worth 7 points.

To extend your 9-resource example a bit:

3:3:3 = 21 points
4:3:2 = 19 points
5:2:2 = 17 points
6:2:1 = 15 points
7:1:1 = 13 points
7:2:0 = 11 points
8:1:0 = 10 points
9:0:0 = 09 points

No problem, good luck!

I like each of the different ideas proposed above as a way to deter player from trying to gain lots of one category. Here are a few more:

- Make the total score equal to each of the categories multiplied together. For example, 7/0/2 is zero points. 3x3x3 = 27. 4x3x2 = 24. 5x3x1 = 15. Scores could build rapidly, which may not be good. The difference between 4x3x3 and 3x3x3 is only 1 resource but the score increases by 9 points. However, you can see that there is a big deterrent to having a lop-sided spread of resources.

- Implement a punishment or "headwind" for players that have too many resources of a certain kind. Thematically, maybe the resources take up different kinds of storage space, and each player only has free storage for 3 units of each resource type. Players over the limit for free storage have to give up 1 resource each turn that they are over as payment for additional storage. Perhaps players can invest in additional storage for resources that they are prone to collect in abundance.

- Make resources have VP values that aren't known until the end of the game, forcing them to collect all of them. Maybe the points per resource type vary from game to game, or only one resource is worth anything. Perhaps there could be a slow reveal of the VP schedule where each resource's VP value is released one at a time, and only every so often. Maybe the values are set at the start, but hidden facedown - in this case, players might be able to pay to see one of the cards to better inform their strategy. This last example then adds in the potential to bluff by making feints towards low-value resources in the hopes that other players will push too hard in that direction.

Edit: I had to add a few more thoughts to this last point. One way to inject player interaction and reduce the perception of chance would be make players pay for resources to be worth more. In an economics-themed game, maybe players can buy advertisements for microwaves in order for them to be worth more VP at the end of the game, presumably because that player has a comparative advantage in making them. In a court-intrigue-themed game, maybe players have to promote certain guilds in the eyes of the king (increase a resource's VP worth) while also having to manage how much influence they actually have in those guilds (increasing amount of a resource).