adding nightmare and sans HHC

README.md

@@ -75,6 +75,7 @@ The chals below are listed with recommended ones first, then the rest in alphabe
 - [IO64](http://io.netgarage.org:8064/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
 - [IO](https://io.netgarage.org/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
 - [Microcorruption](https://microcorruption.com/login)
+- [Nightmare](https://github.com/guyinatuxedo/nightmare) <img src="https://img.shields.io/badge/style-offline-lightgrey.svg">
 - [OverTheWire Behemoth](http://overthewire.org/wargames/behemoth/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
 - [OverTheWire Drifter](http://overthewire.org/wargames/drifter/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
 - [OverTheWire Manpage](http://overthewire.org/wargames/manpage/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
@@ -140,6 +141,7 @@ The chals below are listed with recommended ones first, then the rest in alphabe
 
 - [CTF 101](https://ctf101.org/)
 - [IO07](http://io.netgarage.org:777/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
+- [SANS Holiday Hack Challenge 2023](https://2023.holidayhackchallenge.com/invite)
 - [SmashTheStack Amateria](http://amateria.smashthestack.org:89/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
 - [SmashTheStack Tux](http://tux.smashthestack.org:86/) <img src="https://img.shields.io/badge/scoring-no-lightgrey.svg">
 - [Viblo](https://ctf.viblo.asia/landing)