I'm trying to build a very simple economic model for the blobs. There are two types of items: food and money. A blob can do four things: rest, plant crops, harvest crops, or eat. What makes this complicated is that the blob has to make a tradeoff between present and future and between comfort and wealth.

How can I make it interesting? I don't want one option to be always better than the other.

One way to make blob behavior interesting is a non-linear utility function. Intuitively, the unpleasantness (negative utility) of each hour of work increases the more work you've done. Hour ten is tougher than hour three. Also, the pleasantness of goods (positive utility) decreases for each additional unit. This is called diminishing marginal utility in economics. With this principle we can have blobs that do not always choose the same thing, because choosing the same thing over and over leads to reduced returns each time.

The blob decision algorithm is: compute the total utility function of each of the alternative actions and then choose the highest one.

What I still haven't worked out is how to value the future. Planting crops has a present negative utility and a future positive utility. But how do I value the future utility? Having two farms that can be harvested in six months isn't equal to having one farm that can be harvested in three months and another that can be harvested in nine months. How do I take into account the amount of time involved? How do I take into account the possibly varying price of food? Also, how do I take into account the ability to choose something different (by having free time) in the future?