The trolls are attacking.
You are playing GUNN the Battle Valkyrie.
You need to try to stop them.
You shot light globes at the trolls using the SPACE bar.
One push for each globe.
Use ARROW UP and ARROW DOWN to move the player character.

Game will be over if
* you are hit by a troll,
* you are hit by a red fire ball
* a red troll makes it all the way over the field.

There are 4 levels of difficulty,
change level with arrows left and right.