I think you might be overestimating how difficult we currently have unlocks-to-be conceptualized since I can’t see them creating much of a grind to progress. If you look at this thread and scroll down a bit to the section titled “Unlocks” in the OP, you can see the unlock conditions we have, including proposals for unlocking organelles in a way that isn’t endosymbiosis: Upgrades, Unlocks, & Endosymbiosis Master Thread
If you were aware of these unlock conditions and I’ve actually just spent a few sentences being condescending just now then I sincerely apologize.
I see unlocks as serving a few purposes…
- Boosting replayability. It might take a bit longer for the player to unlock their desired part in a certain playthrough than another based on luck, strategy, the environment, etc.; this can boost replayability and depth, since the player would have to pivot their strategy until then.
- Prevents new players from being overwhelmed at the beginning. If we introduce unlock conditions and base these unlock conditions on phenomena related to the part itself, players will have a more intuitive understanding of exactly when each part is useful.
The second point isn’t really relevant here because theoretically a player with multiple saves has more experience than a player with one. But I think the first one is really diminished by having parts be available across all saves. The strategy-aspects of having the player consider what parts are available to them in the current environment are an interesting dynamic to have in an evolution simulator, and can loosely reflect the fact that, for many groups of organisms, certain metabolic strategies are out of reach in a minimally obstructive way. We definitely do not have to be as demanding or rigorous as evolution is in only allowing mutations to occur on previously existing features, but I think it is a tiny bit uncanny that a photosynthetic organism living on the seafloor could just place down a thermoplast, no questions asked.
There’s also the fact that endosymbiosis would basically be useless in basically every new world if unlocks are applied to every save. Unlocks are also meant to work as a fallback for a player who is unlucky with endosymbiosis; if we allow the player to maintain unlocks throughout saves, then no one would ever realistically utilize endosymbiosis.