A technology or skill tree is the visual representation of the such network and the possible sequences of upgrades a player can take, usually through the act of research or experience points.

Using this tool, you will be able to,

create your own trees in the Techtree Editor Window by creating nodes and dragging connections,
assign UnityEvents to particular technologies/skills that will be invoked when research is complete,
access, track and update the upgrades in an individual techtree at Runtime.

Usage;

Use "Tools" menu -> "TechTrees" -> "Create TechTree..." to create a TechTree item in the current scene.
Select the TechTree item. -> Click "Open TechTree Editor Window..." button in the inspector to start the TechTree Editor.
Click "Create a Tech" button in the TechTree Editor to create new Techs and place in the TechTree.
Click a Tech to select.
Right click another Tech to create a requirement between the Techs. Repeat to remove the requirement.
Drag Techs to move it in the tree view.
You may drag the TechTree into Project folder to create prefab to use in other scenes.
You can have multiple TechTrees in the same scene by repeating the first step. They can use same Techs if desired by dragging Techs into other TechTrees.
You can invest on the TechTree using Research() method and track the progress using isResearched property.
You may set up methods to be called upon a Tech is reseached by selecting a Tech and using the "+" button under "On Research Complete" UnityAction in the inspector.

Features;

Tech trees are non-cyclic unidirectional graphes. The editor checks the unidirectionality continously to prevent users from creating requirement cycles by mistakes.
The tech tree editor continously checks for redundant requirements, making editing the tree a breeze.
The tech trees may be stored as prefab to store. Editor doesnt allow changes in prefab TechTrees to avoid losing your trees.
You can use the UIposition vector of each TechNode to visualize the techtree in the game.

Techtree / Skilltree Creator