We let one particularly hard level slip by. It IS possible, but if you just want to see the ending (SPOILER): https://youtu.be/-5ywlQnP0Vo

The game is too big on my screen

Try to find a page slider you can use to reach the right side of the web page. There should be fullscreen button on the lower right side of the game window.

How does this fit the theme?

You cast spells by drawing a shape in a loop. Each spell has a different loop shape. If you reach a game ending, you might also find there's a final funny detail, which also goes along with the loop theme.

I have no idea what I need to do

There's a grid of 16 points. You can draw shapes to cast different spells. The list of spells is available on the Grimoire button. Click and drag on any point on the grid to draw the shapes.

What do the different enemies do?

Each enemy has a different play style, it's up to you to find out which spell works best! There are enemies with shields (shown as a symbol on top of them) where you could use a shield remover. Others summon little guys, so an area spell would be probably be best. Experiment as you play!