What a fantastic game!
I want to address the issue of how the unlimited production of seedlings seems to lead to a strategic "dead-end" for the player, or, as Rudolf put it, "Alex and myself are keenly aware of the fact that in the end every level can be beaten by exploting the fact that seedlings are an endless resource." I think I have a very unique idea that may become a solution to this problem.
Firstly, I want to make it clear that I don't want to see any part of this game changed. If the creators do eventually decide to add different units or more kinds of trees to address the strategy problem, I think they would only be reducing the game's core uniqueness and limiting its ultimate potential by making it more like other RTSs.
Although the seedlings are said to be "semi-autonomous self-replicating mining machines" they certainly feel organic in terms of their behaviour and growth. But every known biological system thrives only as a part of a much larger ecosystem - and since these "Dyson machines" appear to have a very "lifelike" AI, it is conceivable that their creators designed them to fit into a larger "stellar niche." So here's my idea:
Add a completely neutral, alien "pollinator" species to the game.
I'm imagining something like butterflies. These aliens, like Earth's pollinating insects, are unintelligent animals with their own niche to fill - namely, feeding on nectar and incidentally spreading pollen across the asteroid belt. They will seek out Dyson trees to feed on (any Dyson trees) and they will share the trees' location with others of their kind, much like ants do by releasing pheromones. The pollinators could originate from within the visible asteroid field, or from locations far out of the player's reach.
But, like many Earth plants, Dyson trees don't need to be "pollinated" before they can produce seedlings. However, because of the constant radiation and natural wear and tear on life in space, seedling production will slow down over time if the trees are not cross pollinated with others. Like genes, perhaps the Dyson trees' code gets corrupted over time if it is not revitalized by the introduction of new code used to replace damaged code. In the absence of pollination, each new generation of seedlings will be weaker than the last and will take longer to reach maturity.
Now players would need to figure out strategies to keep pollinators returning to their trees, while taking care to redirect other pollinators away from their enemies' trees. This could potentially be done by creating a breadcrumb-like chain of small trees leading pollinators directly to one's most important asteroids; or by decimating all pollinators in the enemy's part of space; or by creating a sparse and vast net of Dyson trees in hopes of "catching" wandering pollinators. Surely players would come up with many other strategies.
The player would have to plan their strategies from within the confines of the Dyson tree niche, rather than by simply dominating everything they see like one does in typical RTSs. Here, there would be little need for specialized resource-gathering units or population caps, and an increased need for more long-term planning.
The idea of genetic exchange and a larger "stellar ecosystem" carries with it many other possibilities and potential features for the game, but my pollinator concept is the idea I most want to present to the forum and game designers. What do you guys think? Could this feature "solve" the strategy problem by adding another level of depth and immersion?