Level Select:
Start the game with the QUEST:ELD< difficulty 1-5> command line parameter. 

Cheat Mode:
To enable cheat mode hold Caps Lock + D + X + Arrow Down. Press Backspace, then type
one of the codes below to activate it's cheat function.

Function - Code 

     Power-up weapons, both characters - fire 
     Full health - rain 
     Power-up stamina, both characters - magma 
     Round mana gems up to 250 - astral 
     Enable fire, rain, magma, astral codes - prime 
     Level select - ether 
     Invincible, except for spikes, weights, drowning - wind