Supports both ALZ and EGG formats, with limitations (see wiki) as well as encryption and split archives.
Not intended for production use at this time as functionality is incomplete and testing is currently limited. Bugs and suggestions are welcome, however.
The EGG file format is an archive/compression format developed by ESTSoft. It is similar to the ZIP format, but supported certain features (e.g. Unicode filenames, split volumes) earlier than ZIP. It is still in use today, but unless you live in South Korea you probably haven't heard of it. ALZ/EGG files are authored using ALZip on Windows.
using var inputArchiveStream = new FileStream("archive.egg");
using var archive = new EggArchive(inputArchiveStream);
using var firstEntryStream = archive.Entries.First().Open();
EggFile.ExtractToDirectory("archive.egg", "me/output");
Pure C# and completely managed with no dependencies. Compatible with netstandard2.0 and netstandard2.1.