Necronomicon has two types of LARPs this year: Show up and Play, and the Vampire LARP.
For Showup and Play - These are all games played in a single room for a certain amount of time. Check the schedule, show up at the door to the LARP room and join the game! Super easy.
For the Vampire Game - This is an all-weekend game that requires signup in advance. The good news is because the game has multiple layers, a member can join anytime. Sign-up sheets for this game will be at a table opposite the registration desk.