I integrated the token version of Caltrop Core into my Scheherazade concept. The document doesn't talk about d4s a lot, but the d4 "tokens" are an essential part of resource management as you play through the game/tool. In a sense, the "recursive power" the game is based on is "powered" by d4s (it's also why I have a "d4 shape" so prominent on the cover).
https://barondipitous.itch.io/scheherazade-gambit
In my previous two Caltrop Core games (submitted in the 1st game jam), I was much more experimental with the system. Caltrops, Cloak, & Dagger made three different classes using the d4s as representations of caltrops, cloaks, & daggers (since d4s can so easily represent all three), with various rolling mechanics for each class. Platonic Elements goes even further by including not only d4s, but also d6s, d8, d12s, & d20s. Even so, the basic Caltrop Core is there, in the sense that each dice (element) has four outcomes (I'm especially pleased with how this division works well for the d6, because even though it's the only one that's uneven, I was able to justify it for the earth element because a certain distribution makes the rolls more consistent & stable).
https://barondipitous.itch.io/caltrops-cloak-dagger
https://barondipitous.itch.io/platonic-elements