I was thinking to add to the depth of the game, it would be vastly interesting to begin the game in a defined world (A multi-nuclei cell.) with many organelles, proteins/enzymes, and begin life as a simple protein(virus).
Then as you become a more complex protein you add other complex protiens to your chain, and attack other organelles, nuclei, and begin forming a lipid-bilayer for protection against other enzymes in the cell you’re inhabiting.
Then when you burst free from your host-cell, or become it’s replacement nuclei, you then proceed to play the game as a cell.
Adding protiens like lipase, to destroy a lipid bilayer of other organelles. At the protien-level even the smallest cells would seem enormous, despite being inside of a massive cell, the smallest organelles would seem massive to you. Then as you add proteins, replicate, and add molecules to enhance your complexity and continue your growth, by the time you become a full-fledged cell it’d have felt like a journey.
Discovering proteins, molecules, viruses, et-cetera would be incredible. Basically the same game, but at a much smaller scale, even lipids themselves would be like obstructions. So moving into becoming just a single-celled organism would feel like a monumental achievement. Going from a molecule sized self-replicating rogue protein to a cell would be so cool.
Having your ancestors becoming enemies after 20 or so generations would be super neat to, seeing your past evolutionary states becoming volatile creations depending on the path you chose to take during those iterations.