I've been thinking, and here are some ideas that I consider fun that you could add to this game.
They could be in different modes or whatever.
Bonus ghost: A normal ghost, but every time it curses you, you get 1+current curse level points! Can you survive long enough to get good points from it?
Unstable: This could be a mode or something. Every second, every object or entity has a 5 or so percent chance to teleport to a random position.
Skeleton, enemy:
These have short bows, and they run away from you.
When there at a safe distance, they load up and shoot at you, requiring you to jump to avoid them.
You need to trap them against a corner or something to kill them and get those 2 points!
Magnetic cannons:
These are normal cannons but when they fire a ball, it simply rolls randomly around the board until it hits something. Maybe you, a wall, a troll, or a cannon. Probably drops a point when it dies and expires after 20 seconds.
If one is near you, you may be able to attack it to send it rolling in the direction your facing.
There could be a mode where you can't attack anything besides cannon balls and you must relie on aiming with cannon balls to get points!
Battleaxe: It's a power up, and while you've got it, you can attack trolls.
All I can think of for now.