I'd vote for something even simpler, actually, to avoid us ending up playing Accountants & Auditors.<br/><br/>Like, 'you earn 1d10 Soul Points per week' simple. If you don't buy anything, earn an extra 1d10 Soul Points'. Reduce the costs of buying things with souls to scale accordingly with this, but keep the rate of soul intake as flat as possible. A Soul Point could represent a thousand or ten thousand or million souls, but stripping off the extraneous zeroes reduces bookkeeping.