It's been said many times, but BYONDimes need to come back. Micropurchases are the way to go with video games.
I had planned to do one myself for Iccusion games, but a currency that works across all games on BYOND would be easier to sell. Not to mention BYOND would get paid also.
I know there were problems with it before, but here are a few suggestions to make it work this time around.
Only accept credit card and PayPal payments.
Only allow certain games (listed games for example) to accept them (aka BYOND members).
Only allow trusted developers to withdraw earned dimes off of BYOND (maybe a minimum withdraw limit).