Good luck to you! When we implemented in our K12 and had a lot of skeptics, my best tactic was to find the people who were interested and willing to make a change. These people jumped in, learned, and talked it up to others. Students also shared what they were doing in so and so's class which helped to bring more people into the fold.
I've seen some really neat gamified challenges. I think there might even be one in the commons that you could import and modify for your instance. I know I attended a session at InstructureCon 23 that demonstrated a classic video game theme with challenges the teachers could choose to complete. They earned their names into drawings for conference attendance and such. I thought it was a clever approach.