Overall it sounds like a WoW RTS. Which sounds fun but oh so difficult.
I agree with the above comments and they offer good advice.
You are encountering an issue I am quite familiar with, wanting the fruit without planting the seeds.
No goal is beyond reach, but you need to put in real work to get anywhere worth getting to.
You need to have the proper programming ability, content(graphics and sound) creation ability, game design skill to create an idea worth making, and game development knowledge to know how to piece it all together.
Set smaller goals that still capture what motivates you.
There is a lot I'd like to say but since you are asking about game design I'll provide an example of how I would approch designing this game.
A design document is a reliable way to design your game, you fill it with pictures and ideas, and organize it for readability and sex appeal.
The following is a vastly simplified but ironically fleshed out design.
You would add more to the design as you imagined new things, keeping it organized and consistent.
You could add more weapons. You could describe what combat stats the champion has. Add a new resource (gold?). etc,etc.
This is a foundation and when designing its important you record your ideas, flesh them out, and keep them organized.
Civilization Uprising (Working Title)
1. Summary
2. Technical Summary
3. Gameplay Summary
4. Reference Material
1. Summary
A real time strategy game where players control a village of settlers as well as their champion. Players must support their village as it grows while their champion defends the lands.
(This briefly describes the game while setting context for the gameplay, settlers need food, water, lumber to grow their new settlement. A champion represents his people, fighting on their behalf, and defending them gives an excuse for him to go raiding and you only have to worry about 1 character having all these special traits)
2. Technical Summary
The game is in 3D, it has an isometric perspective, uses simple lighting, and the player uses a mouse and keyboard to control multiple units. The settlers, champion, wildlife, and enemies have AI. The collision and physics will be simplified.
3. Gameplay Summary
The Environment: The environment consists of watering holes, trees, and caves.
Watering holes provide 2 water and do not dissapear.
Trees provide 2 lumber, spawn wildlife, and dissapear when harvested.
Caves spawn enemies.
Wildlife: Neutral wildlife like bunnies and dear roam the environment.
Bunnies have simple ai and provide 1 meat.
Dear have simple ai but are faster and provide 2 meat.
Enemies: Aggressive enemies inhabit the caves.
Wolves and trolls are the main threat.
Wolves leave the cave, hunt wildlife, drop 1 meat, and provide 10 xp.
Trolls do not leave the cave, kill settlers who enter, drop 1 iron, and provide 38 xp.
Settlers: Settlers can be given many tasks, once given a task they use pathfinding AI to find their way to their target.
Settlers can collect lumber from trees, removing the tree.
They can collect water from watering holes.
They can hunt wildlife.
They can build new buildings.
They can also attack enemies.
They have many stats including, health, attack, defense, move speed, attack speed, etc.
The Champion: Champions have the same intelligence as settlers however they have special traits and will not do some tasks.
They can hunt wildlife.
They can attack enemies.
They can wear armor.
And they can wield weapons.
They have additional stats such as mana, health regen, and critical chance.
Population: The population cannot excede 5*Number of Houses.
When the number of settlers is less than the maximum new settlers will spawn each minute.
This occurs when a new house is built or when settlers die to enemies.
Buildings: There are 3 major buildings; Houses, warehouses, and the foundry.
Players begin the game with 1 warehouse.
Houses are 2x2 tiles large, they cost 6 lumber, take 20 seconds to build, increase population by 5, and can store settlers.
Warehouse are 2x4 tiles large, they cost 12 lumber, they take 30 seconds to build, and they store meat, water, lumber, and iron.
The foundry is 3x3 tiles large, they cost 10 lumber and 4 meat(why? because.), they take 1 minute to build, and they provide a champion weapons, ammunition, and armor.
Crafting: When iron is obtained it can be used at the foundry to craft goods for the champion.
Great Sword costs 4 iron and provides +3 attack.
Iron Helm costs 4 iron and provides +3 defense.
Bow costs 2 iron and provides +1 attack and +5 range.
Arrows cost 1 iron for 10 arrows.
Staff of Lighting costs 2 iron and 10 water(why? because!) and provides +10 attack, +3 range, and -3 speed
4. Reference Material
Age of Empires 2: http://upload.wikimedia.org/wikipedia/en/b/b6/Age_ii_feudal_age_celts.jpg
This depicts the level of graphical fidelity we hope to reach and can inspire many of the village mechanics, combat, and ai.