Milestones

VPlay.milestone("ach.first-delivery");   // once per player, rewarded by VPlay
VPlay.milestone("level.2");              // matches a "level.*" rule if we set one

Ids look like ach.first-delivery or level.2. We register the rewards, and can use patterns such as level.*. Each player can earn each id once. A reward can be held for a short while (for example until the account's email is verified, or when a daily limit is reached) and is paid automatically later. An id we have no rule for is ignored.