One of the greatest achievements in the Doom history was definitely TeamTNT's Icarus project. 32 maps in the same quality and style as we already know from Final Doom. Good things come to those who wait: Almost 2 decades after it's release, the mapper Eternal released a map pack called Icar2015 which can definitely be considered as spiritual successor - just with a bit more quality. The project has been posted by entryway and can be found here (as well as on /idgames). For some nostalgic retro feeling, grab the file and play it, this is gread Doomin'!