Long time listener, first time caller...I'm Snyder from SW Ohio and I like long walks on the beach...no wait, wrong group...Been DMing for about 5 years now and looking forward to learn more and make my games better. 5E
As a fun introduction...I give my players stupid little puzzles that have no bearing on the game. If they solve, it comes with prizes or bonus levels.
In my last session, my players found a coin on one of the ̶m̶u̶r̶d̶e̶r̶h̶o̶b̶o̶e̶d̶ bodies from an encounter. On one side was the sigil of Baal/Bhaal and the other a figure with a peg leg. They stewed on it and someone said Diablo 2.
I then held up a print out of the difficulty selection screen of Diablo 2 an put the secret cow level on the table. The bonus was refilling 2 spell slots, charges, abilities, or features, their choice.