I really enjoyed Shovel Knight when it released last summer click here to read my review. This DLC looks substantial and almost like another entire game and looks great. Read the details on this big DLC below:

Shovel Knight: Plague of Shadows is a free expansion for Shovel Knight, a sweeping classic action adventure game that won over 70 Game of the Year Awards in 2014. You play as Plague Knight, the villainous master of alchemy, in a quest all his own. Using his maniacal scientific mind, Plague Knight is seeking to concoct Serum Supernus, the Ultimate Potion. However, to retrieve these ingredients, he must extract them from his former allies… the villainous knights of the Order of No Quarter! World class platforming, music, storytelling, and art all return in Shovel Knight: Plague of Shadows; an explosive quest with a new play style, new story, new bosses, and more!

An adventure featuring a New Star: Plague Knight!

See your favorite game from a new point of view! Play as the explosive trickster Plague Knight with new story and gameplay!
Join Plague Knight on his quest to overthrow the Order of No Quarter! Become the ultimate alchemist… and maybe find some romance, too…

New Gameplay

Explode onto the scene as Plague Knight! Use explosives, bomb jumps, and alchemy to blast your way through the game in a whole new way!
Crafting Comes to Shovel Knight with the Alchemy System! Collect loot and use alchemy to craft equipment and power-ups
Collect new recipes and reagents to become the master of disaster!

Remixed Game Content

New objectives and enemies!
Brand new areas and new paths through classic levels!
New bosses!
Is your science up to snuff? Take on Plague Knight specific challenges with new Feats!

Yacht Club Games, Llc.

Source: Yacht club website