Starting the game:
Choose a character, then click survival mode and the difficulty you want.

Controls:
W,A,S,D to move
Aim with mouse, Right and Left click to cast abilities
Space opens/closes the menu and pauses the game
In the menu, you can use gold to buy upgrades for your character
Hover the buttons and abilities for descriptions

Wizard:
Left-clicking an ability maps it to left-click in game
These are cast as described
Right-clicking an ability maps it to right-click in game
These cast at an increased cost and casting time, but also greatly boosts the effect and damage

Archer:
Only the rightmost ability is mapped to right-click
The rest are divided into firing styles and arrow types
you choose 1 of each, the costs and effects are added to each shot fired

General:
Abilities that can be channeled are used by holding the mousebutton for the duration
You cannot change abilities in the menu while casting 
Potions can be used with the number keys 1-4

Future planned implementations:
The melee Paladin class
Story mode
Varying maps
New enemies and abilities
More complicated ai
Respaws and X lives per playthrough