We have considered charging for the HUD but as many have told me, people expect free in SL. We've considered creating add-ons to enhance the user experience, but since these games are part of a contest we felt it would be unfair to others. So we have a donation box for the programmer which is a very minimal amount, and I sell costumes that I used to make the NPCs for sale so they can "play" the part, but mostly the biggest payment is probably brand recognition from my clothing store which just about covers tier fees and purchases made for the game.
I couldn't bear spending the amount of time I have building these games, charging for them, and no one showing up. The reason I started working on these games in the first place was to create a new user experience in SL that would make it fun again, not for me but for everyone. Additionally, these games have a certain life span. We can spend a month or more building a murder mystery, for example, and then unless we constantly advertise it, it quickly becomes forgotten. And we don't even charge. If we leave the mystery up for longer than a month, any traffic afterwards is barely a trickle.