The Grid

As mentioned in Section 4.2.2, cells in Cosmos live in a discrete two-dimensional spatial environment (the `grid'). At the start of each time slice, a number of energy tokens are deposited to each position on the grid (see Section 4.5.2). Cells can collect these energy tokens by using the et_collect instruction (see Section 4.5.3). If energy tokens are scarce at a cell's current location (or indeed for any other reason), the cell (to be precise, the whole organism) may move around the grid (see Section 4.5.4). For multicellular organisms, each cell must occupy a different grid position, i.e. all organisms are `flat' (cells cannot pile on top of each other in the same grid position). However, cells from different organisms can occupy the same grid position. What this means is that all organisms are flat, but they can `slide over' each other, and in this sense the environment is two-and-a-half dimensional.