as it stands you can cheese this game extremely easily by brewing with only flaked corn or rice. Which ofcourse would not have worked because it would have 0 DP.
But far as I can tell DP is not simulated, so maybe it should?

Also, beermaverick has this concept of a "batch max" that describes how much a type of grain should be allowed in the grain bill, if one were to go over this the taste would be off, or mashing will be harder. Maybe that should also be modeled.