Too many good .NET OSS projects get abandoned. I've brought NDepend.Path back to life: it's now updated to .NET Standard 2.1, all unit tests pass, it has a new CI / CD process, and I've taken ownership of the nuget package: https://github.com/endjin/NDepend.Path & https://www.nuget.org/packages/NDepend.Path/
I did the same last year with the *awesome* Argotic Syndication Framework. So much work went into it 13+ years ago, but it just lay in CodePlex gathering dust. It's core to data processing in @AzureWeekly so we took ownership, upgraded, and released: https://github.com/argotic-syndication-framework/Argotic/wiki/consuming-an-rss-feed
If you feel like adopting an abandoned OSS project, I'd highly recommend migrating it to its own GitHub & NuGet org, so that it's easy to bring in new contributors. http://NuGet.org as matured so much in this aspect over the last few years.
Also, upgrading to .NET Standard now seems to be a quite straightforward process and it's really east to build nuget packages, add source link etc to light up all the .NET super powers.
To claim an abandoned NuGet project:
1. Contact the author to request co-ownership of the package.
2. Check the “Send me a copy” box & send [email protected] a copy of the email.
3. If support do not get a response after 30 days you will be added as a package author.
1. Contact the author to request co-ownership of the package.
2. Check the “Send me a copy” box & send [email protected] a copy of the email.
3. If support do not get a response after 30 days you will be added as a package author.

And @ythos has been making some nice small gestures by shipping contributors to our Corvus OSS project special mugs - much cherished internally!
I'd love to move towards proper sponsorship & bounties, but baby steps! Some of the work that @GeoffreyHuntley has done in this space is great and should be replicated.
This is probably a good thread to finally say that after 18 months of much pestering of the powers that be, I'm delighted to announce that @endjin is a @dotnetfdn Corporate Sponsor https://dotnetfoundation.org/#corporate-sponsors
We've done lots to support free to access events for the .net ecosystem over the last few years, but I deeply believe that a centralised foundation can offer more support (financial, legal, marketing, logistics) than any single contributor. We're stronger together.