OP, Spies are fun. You're fine. Try a game like this:
http://www.target.com/p/chrono-bomb-game/-/A-17281352
It's more of a obstacle course. If you hit the strings (AKA laser beams), it makes a noise.
Think secret codes, you can buy or make your own cypher code:
https://www.savvyhomemade.com/making-a-cipher-wheel/
You can write on a poster board telling what the key letter is and spaces for the phrase and they can solve the puzzle.
Dress up--fake mustaches, eye patch, beard, wig, hat, funny glasses--you can do a photo booths for selfies or fake spy passport.
Give out a puzzle for a party favor.
http://www.orientaltrading.com/puzzle-balls-a2-12_1801.fltr?Ntt=puzzles