Marsh Davies reckoned that TowerFall was a bit good when he reviewed it back in 2014. It's since been expanded with the 'Dark World' DLC, which added quite a few new features to the multiplayer arrow-'em-up. All was relatively quiet on the TowerFall front until a couple of days ago, when developer Matt Thorson added support for the Steam Workshop, meaning you can now create your own towers, and share them with your friends/inflict them on your enemies.
You'll need that Dark World expansion to be able to use the level editor, but it's a free update once you have it. To celebrate the occasion, TowerFall is currently 75% off on Steam (while Dark World is 33% off).