Gameplay Concepts
You have five gems.
These gems are hidden, safe in a cave, because the world is full of troublesome adventurers, all of whom want your gems for reasons left undefined.
These adventurers will come in waves, with the aim of marching down the road to your gems and stealing them.
In order to stop them, you need to build towers on the cliffs along the road, armed with various weapons to destroy your enemies.
Resources
There are two resources, gold and mana. Gold is spent to build and upgrade towers. Mana is spent to cast spells.
You are given some gold at the start of each level, and can acquire more gold by killing enemies. Certain skills can also give you extra gold.
Mana, unlike gold, cannot be acquired directly, and has a maximum capacity. You will generate mana over time, until it reaches your mana cap.
Terrain
What towers you can build depends on the terrain. There are three types of terrain: grass, snow, and rock.
Each one supports a unique type of tower – a Den, a Crypt, and a Temple, respectively. This raises some very good questions about monster zoning restrictions. Don’t expect any of them to be answered.
All of these terrain types come in a forested version as well. The only difference between a forested tile and a non-forested one is that you can’t build on forested tiles. No, this does not make the terrain distinctions between forests meaningless, for reasons we will get to later.
In addition to these, there is a fourth, special terrain type – high ground.
High ground exists so that choosing which type of tower to build is more than just building the ones that the map terrain will let you. Any type of tower can be built on high ground (which only raises further questions about monster zoning restrictions) and those that are will receive a boost to their range and damage.
Proper use of high ground is vital to success.
In addition, any of these terrain types may hold mana pools. A tower built on a mana pool will increase the speed at which you generate mana.