in order to make my own launcher, I don't need to know html5. The roblox client only requires a simple Webserver (like a small PHP/MySql hoster on localhost). If I were to create a launcher from scratch, I would focus on building a Webserver on localhost that is integrated into the launcher's exe file. It's easier for me to use someone else's code (which is open to everyone by the creator) and build upon it.