I’m trying to implement a comboing system into my game and it seems that the best way I found out on my own are tree data structures. But I can’t find any good examples or any examples at all. I’m possibly not looking hard enough but any possible help would be greatly appreciated.

Something like the image above except the player has a small time to input to continue the combo tree. I know I could Input all the kets in the Input Manager but I’m doing this for Mobile and so Im trying to find a way to do this procedurally. I tried using Lists but that won’t work.
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I kind of want a walk through it and figure a few things so I can actually learn to do this is future projects.