Here is a full ROM hack for Darkwing Duck. New levels, 1 new weapons, new bosses, and new graphics have been added. The language is Japanese, but you should be able to fully play the game with no issues.
UPD (Dec,12,2021): In v1.1 various bugs were fixed, the original music was returned and some places on the levels were changed (it became easier to pass).
The archive contains 2 patches - "Easy" and "Hard". In "Easy"-version there is no additional 4th weapon and it is not possible to collect all additional weapons and switch between them. Also, the AI of the bosses here is the same as in the original, unmodified game.
Darkwing Duck (USA).nes - NOINTRO
CRC32: 307D0FC4
MD5: 459837F4E8FCBAF29BD66ED926B6882E
SHA-1: 7188D8CE3D8D2A0DCD7B10FBC23A6F84FA9C4161
SHA-256: B7FFF97F34D7142765685C6505AD54285CFD7E847E6943BC53E432C4F25FA49C