"Strategy" and "Tactical"
Starting with specifically strategy games. The core experience for the player could be described as A game that emphasizes the cumulative result of a players choices. In design this boils down to feedback loops. Build more units for resource gathering, you have more resources to build units for resource gathering.
In many strategy games, this is represented as economic choices. The best example of pure strategy games is probably Tower Defense games. You earn resources, and then spend them. But you don't typically actively make decisions about the individual fights that happen during waves of enemies.
So for strategy in general I'd say the choices available to the player and how those different choices compound to a final result is the key.
The focus of tactical games could be describe as Maximizing fixed or limited resources to build the best outcome.
My favorite example would be the Myth series of games. You never actually build new units (maybe you find some, but they are units already existing in the level).
Civilization series, Age of Empire series, and *craft series all have economics at their core. You choose how many workers to build to increase your resource gathering vs. defensive or offensive units. You also decide to spend on your "technology tree" in all three, with some variation. That is strategy.
These game are also tactical. In Civ, you build up cities and train units and this leads to what resources you have available for battles when they occur. That is the strategy part. Tactical comes to play with your placement of units and their preparation. Battles may last only a few turns, and it's not likely that you'll be able to bring many more units to that battle. You have to make the best with the resources you have and the environment.
Tactical Strategy Elements
So, strategy involves a series of choices that continually build upon each other. Tactical is focused on maximizing effectiveness of resources.
Most important elements then affect both:
- Economic Decisions. Some form of compounding decisions. Typically this is based on economics, with resources like gold or food or vespene gas. Then add different things that can be done with the same resource, forcing the player to choose one of many uses.
- Utilization of Spent Resources. Typically these are mobile units that can engage in fights with other unit. The player has chosen to build these units, this is the compounded outcome of their strategy effecting their ability to perform some action.
- Tactical Advantages. Constraints that the player can react to, in order to maximize the use of those units. High ground, visibility, etc. just so that it isn't a numbers game. Otherwise the strategy portion of the game will fall into gathering as many resources as quickly as possible. Starcraft does this very will with its highly varied races and units.
Tic Tac Toe is a tactical game. Limited spaces, trying to out position your opponent.
Economics do not always mean strictly money. In Starcraft, there is a cap on the number of total units you can have. The units are part of the economy.
A lot of the rest are aesthetics. Real Time Strategy games promote a more chaotic feel. Real Time Chess is absolutely crazy.
Grid based games tend to promote more tactical gameplay as it is easier for players to judge distances or terrain effects. Civ tiles provide widely varying differences in effect. Without tiles it'd be hard to know which units are receiving which effects.
Turn based games are meant to promote more planning. They can provide a much deeper set of strategic decisions to the player. Micro management in Civ means carefully planning what citizens are doing what. Micro management in Starcraft is a matter of how quickly you can give tactical orders to your units.
I've got to do some digging for specifics but "Game Mechanics: Advanced Game Design" by Ernest Adams and Joris Dorsman is a great book for understanding and modeling economics in games, they also discuss the Machinations tool which is awesome for designing and testing.
Also "Game Design Workshop: A Playcentric Approach to Creating Innovative Games" by Tracy Fullerton talks about how to break game down to the smallest parts and understand them.
Those are just two of the books that I've read that I can remember have some relevance. I'll try to find specifics in each to highlight when I cna.