What makes a game difficult?

When creating our game Gnomin' we took inspiration from games like Getting Over It and Get Out Joey. These games are usually quite difficult, but should still be fair. We hope to be both, and would like your opinion! Is our game difficult enough? Is it too difficult? Are there any aspects you find unfair?

The leaderboard

Similar to our other games, Gnomin' has a leaderboard to motivate players to compete with each other. At this moment, I am still first place, I'd like this to be changed! Help Ink the gnome get to the end of the cave as fast as you can and beat me, Korcalius and Meep out of the top 3!

You can play Gnomin here: https://ldjam.com/events/ludum-dare/56/gnomin