Here are my themes and words. I went for the escalating targets of a cybercriminal.
Easy:
Theme: University Transcript System
Words: pregame, kegstand, rager, weeder, cram
Medium:
Theme: Classified Bio-tech Research Center
Words: genetics, organism, synthesis, molecular, patentable
Hard:
Theme: CIA Cyber-Warfare Division
Words: hacktivist, vulnerability, honeypot, ransomware, centrifuge