I feel like crystals were just not necessary. Fun idea, but it didn't really change the game all that much. The purple stone on the other hand felt way cooler because I kept seeing it everywhere and when I was finally able to use it, I zoomed all the way in and implemented it from there.
Also, in the second to last area, the resources needed to make Space Ants don't increase per ant, making it trivially easy to populate space with ants. It might be a feature, but for me, working to make the previous areas super efficient, populating workers in the next area up ASAP, it felt not as good as the previous areas.
Overall, I had a blast! Good game!