Guide is short and comprehensible.
I got mine up and running in about 20 minutes No dealing with cgNAT, IPv6 compatibility, domain name, signing up with DNSs. It just works.

I2P is a more sustainable darknet protocol than Tor and I2PD is the (kinda) new lightweight implementation written in C#.

Tip for those who have IPv6, I highly suggest you enable it in the conf file, usually /etc/i2pd/i2pd.conf.