Use the arrow gets to move around.
You can pause the game at any time by pressing the escape key.
> From the pause menu you can resume, restart, or return to the main menu.
Coming into contact with an enemy while they're on equal or higher ground than you are will result in you taking damage. If your health reaches zero, you lose the game. Simply jump on top of an enemy to defeat/damage, with the only exception being the final boss.
There are many nectar drops scattered around the map. Picking one up will fully heal you and give you a small boost to your score. Use these strategically!