Doomguy: short, to the point. "who is that?" it's Doomguy. "what does he do?" he does ᴅᴏᴏᴍ.
The Doom Slayer: overwrought, generic. "omgz, xXx_the_d00m_slayer_xXx livejournalled on the wall of my MySpace!!!11!!1"
Mastodon is a server for a federated social network: everyone can run a server if they want to, including me. So this is a Mastodon server for me (Vierkantor) and my friends.