Split what isn't enough to go around, then meet the veil of ignorance.
Each case hands you a fixed pool of water, doses, grain or credits and four claimants who each need a slice. You allocate the whole pool first behind a 'veil', not knowing which claimant you'll turn out to be, and then again once your role is revealed. The game compares the two splits to expose any self-interest that crept in.
Fair Share turns a classic thought experiment in distributive justice into a game about what a fair division really means.
Allocating a fixed pool among four claimants before learning which one you are is John Rawls's veil of ignorance implemented as a rule.
Deciding behind the veil is the original device and the whole argument.
Rawls's claim is that a just arrangement is one chosen without knowing your position in it, because self-interest cannot then distort the choice. Whether people actually choose differently behind the veil is testable, and this is a way to test it on yourself — which is a sharper encounter with distributive justice than reading the argument.
Fair Share is an original free browser game that turns a classic thought experiment in distributive justice into a daily allocation puzzle. There is a fresh Daily case for everyone plus an endless Practice mode.