1. A system comprising: a credit administration facility for administering any a priori promotion credit and any a posteriori credit associated with a player account, the credit administration facility being operable to compute: (i) a total balance of the player account as a function of wagers made by the player on house edge services, in which a house acts as a banker, and wagers made by the player on peer-to-peer services, in which the house does not act as a banker but levies a transaction charge; (ii) play through achieved for the any a priori promotion credit; (iii) play through achieved for the any a posteriori promotion credit; and (iv) a cashable portion of the total balance, wherein the cashable portion is affected by play through achieved for the any a priori promotion credit in accordance with a first play through requirement and by play through achieved for the any a posteriori promotion credit in accordance with a second play through requirement.