Seems like a legit series of challenges to me. Challenge 1 could be scanning a range of IP addresses for a host with a certain domain name. It could be as complex as Challenge 10 having to scan 1 IP address FROM another IP address with IP and mac spoofing. Or even scanning a range of IP addresses to find a certain host running SSHv1 or Port 23 open.... etc.
If everyone thinks this would be a good addition to HTS, maybe I can devote a little more time into my idea!!