Resources

We've all played the game where a building costs 8 Wood and 4 Stone to build. Even the classic computer game Starcraft had two costs — minerals, and vespene gas. Why?

Having these two separate resources doesn't really achieve anything, except making things a bit more complex to afford.

Resource identity

Each resource should have its own fundamental identity, tied to its own system or important game concept.

In our wood and stone example, maybe wood buildings produce resources, while stone buildings are worth points. This actually means something now. As a player, I don't just want to get more resources. I want specific resources, depending on what I want to do. If you have resources that aren't fundamentally different, you should probably merge them. Even in this example, wood and stone are fundamentally both just different building resources. This would be fine, if building buildings was the central part of the game, and each one of those two resources could be given an individual identity within that.

Unless a game is about resource conversion, no resource should be easily and repeatably convertible to another resource.

Err on the side of having less resources (unless the resources are the core of the game.)

Don't add more resources to your game. Instead, add more systems, each of which likely has only one resource.

"Block" is a common score I see in combat games. It reduces damage. Yes, it's different to some kind of damage score, in that it's defensive, but it's very much equivalent to the health score. Also, it's boring.
In my gangster game, there are four clearly distinct resources. There's health, which keeps you alive, and in the game. There's money, which buys entry into powerful places. There's rep, which wins the game if you get 10, and there are gang members, which cause you to do more damage to opponents. You could argue that your health and the opponents' gang members are related concepts, but they're not that close. The resources in this game all correspond to different systems and concepts.
Wingspan is a great game, but it has its flaws. Some bird cards will let you tuck cards underneath them. Others let you put food tokens on them. However, tucked cards and food tokens are all simply worth one point. These two systems are usually identical. I would've made the placed food tokens usable by lots of other birds, or have some rule difference. Or, I would've just abolished the tucking of cards, and just used tokens some more.
In my farming game, stone is for buying buildings, wood is for expanding your land, food is the general resource, and gold is a special resource that allows you to use a taken space.
Catan has five resources, and they're not that distinct. However, it's a game *about* getting and trading for the right resources. As a core system of the game, it's appropriate that the complexity be high here. Most other games are not about their resources, and so they should only have distinct resources.
My farming game originally had eight kinds of trees, and five kinds of crops. I thought this would add depth. This just made the game about the fine details of each crop. Now there is only one type of tree, and one crop. This mass simplification freed up a whole lot of space for cool new systems like cooking and houses, and new resources with genuinely novel functions. The game is significantly *about* resources, so each resource doesn't need to be for an entirely separate game system.

What should your resources be?

Choose the simplest, most obvious resources. This will make your game feel more real, as your game objects will tie logically into those resources.

Generally, you want to choose things like health and money. If your game is set in the past, you probably want wood. You may also want things like stone, gold, and food (or equivalent.)

Also, focus on the theme of the resource itself, not its production. I'm not keen on "ore" as a resource. Yes, ore is technically what you dig up, but it's far less thematic. Just let the player dig up iron.

Also, try to choose resources with multiple functions.

In my farm game, I could've had swords. Instead, I chose axes, as axes are both a weapon, and useful for cutting down trees. When I later decided that axes were no longer required for cutting down trees, I made that resource into a spear. Now, you can still fight with it, but you can also use it to catch fish.

I added salt as a resource. You dig it up, and can use it in cooking. However, you can also use it to make a salt lick, for your animals.