A Ranger's Cycle

Fight off an endless horde of skeletons as a bow-wielding ranger in order to protect the tree you were born from. As your mana increases, you can use the number pad to cast different spells and abilities. Pressing 1 on the number pad requires 5 mana and will cast a damage dealing fireball. Pressing 2 requires 10 mana and casts a long beam that can damage multiple enemies. Pressing 3 will require 20 mana and will freeze the skeletons in time for a moment. Pressing 4 will require 30 mana and will add more life to the tree, though be careful because it starts at 1 hitpoint. Finally, if you manage to make it to 40 mana, you may press 5 and restart the cycle of life that held back the skeletons before and gave birth to you. 

You use the arrow keys to move and jump, and you use left-click for your main weapon, a simple longbow.