We've been at this a long time now! Over the years, we have found that vanilla Minecraft was too limiting in what we wanted to do as a server. We decided that we needed to develop our own launcher in order to accommodate for our continually growing needs. Our launcher acts as a platform through which we can easily modify the base Minecraft 'game', adding a number of custom blocks, texture packs etc.
As long as you have a legal copy of Minecraft which verifies via the Mojang servers, you should be able to use our launcher without issue. You can purchase a digital copy of Minecraft here.