Malasombra is the work of a group of Spanish homebrew developers called 4MHZ, who are perhaps best known for their work on Amstrad CPC titles like Baba's Palace, Operation Alexandra, and Profanation 2.
It appears to be the first game the group has developed for the NES and is an action-adventure sidescroller focusing on an aspiring, young wizard named Pirou, who sees his beloved whisked away by an evil sorcerer named Malasombra on their wedding day.
The story follows Pirou as he sets out to collect the pages of a powerful grimoire, to unlock new transformations, which will hopefully give him the power to defeat Malasombra, reverse the sorcerer's evil spells, and recover his bride-to-be from the jaws of danger.
It all sounds really promising, with the only downside being the "live-action" trailer the team has put together, which seems to utilize an awkward AI voiceover in the style of Stephen Fry.
If you want to back the project, the digital edition costs €10 with a copy of the ROM and a PDF of the game's manual. The complete-in-box physical edition, meanwhile, is priced at €59, and is said to include a cartridge that has been "built to last with cutting-edge technology", utilizing flash memory to save your game permanently and a custom mapper to ensure "full compatibility with original NES hardware".
Here's a link to the project's Kickstarter page.