Happy Halloween! This PPT will help introduce your students to the 'Level Up' game (also known as Evolution), which will let them wander the classroom, mingle with other students, and play a game (all while encouraging them to practice the lesson content you choose to incorporate into the activity!).
The game rules are simple: act like a Halloween character (to show other students what level they are); pair off with another student at their own level; practice the dialogue or expressions you want them to learn; play rock-paper-scissors to see who will level up; then repeat until they get to the highest level and play rock-paper-scissors against the teacher to win the game.
I've used this game as a speaking activity with EFL students (for example, one student might say 'Where are you from?', and the other might answer 'I'm from France.'), but if you use your imagination you can adapt it to anything from math (one student gives a problem, the other solves it) to science ('What's the largest planet in our solar system?', 'Jupiter') to social studies ('What year was the Declaration of Independence written?', '1776').