Algodoo

A cell sandbox game with 2 links and 7 types of cells which die at 1 u of energy. (below energy measurements are at 10 energy, because energy usage increases with more energy aka size)
Plant cell: Creates energy (produces exactly 0 energy at 20 u).
Protector cell: Cannot be destroyed by the destroy cell. 3 u/s
Swimmer cell: Swims at 0.2m/s^2. 1.5 u/s
Destroy cell: Eats cells and takes their energy. 3 u/s
Energy storing cell: stores 100 units of energy. 0 u/s
Secreting cell: secretes sticky strands. 6 u/s
Dash cell: dashes at 6m/s^2 for 1 second when encounters threat. 1.5 u/s, and 6 u/s when dashing.
Reproducing cell: reproduces if it has more than 12 u of energy. 3 u/s.
Eating cell: Eats food. 3 u/s.
Sensing Cell: Senses the thing in its _DetectedSubstance var, which can be "enemy", "sticky", or
"foodsmell", or one of the substance channels "1", "2", "3", etc. the _OutputBase var is the base output of the cell.
the _OutputMultiplier var is the multiplier of the output. the _OutputChannel can be "1", "2", "3", etc. but it has to be in quotes. 3 u/s.
Controlled Mover Cell: a controlled mover cell that has basically the same vars as the sensing cell. 0.75 u/s.
Brake cell: brakes its angvel. 3 u/s.
Nutrient Transfer link: transfers energy between cells.
Physical link: Just... a physical link.
Some pretty cool things can be made with this, what can you come up with?