Daily play rewards could remain as a way for Tix to return. Boot up your first game for the day, get Tix. The easiest way to prevent bots is to not allow users to sell items for Tix or trade them. Have those monthly items you mentioned be the only thing Tix can be redeemed for.
The incredibly public nature of Twitter means that anyone else can also respond with their own sort of feedback that may also add to the conversation at hand, as seen here.