I've just finished designing the skill tree so now seemed like a good time to talk about skills in the game!
Starting off the just some basics about the skill tree, it works like how you would expect a skill tree to work - you level up and that grants you a skill point to unlock a skill in the tree. Hovering over a skill will show a small clip of that skill in action alongside its name and a short description. You can also unlock any skill in the tree, there is no specific order that you have to unlock the skills in. For instance, you could unlock the bottom skill in the "Melee" branch before unlocking the top skill, the choice is completely up to you.
As shown above with the "Cardio" skill, unlocking a skill will turn the background of the icon white. There is also a mystery branch on the right side of the image, I won't reveal what it is yet but you'll eventually unlock the branch by progressing through the story. Now I'd like to list off the current names of the skills, I'll let you try to guess what the all do though. Starting off with the melee branch from top to bottom we have: Rapid Punch, Dash Punch, Electric Knockback, Electric Stun, and Shocking Grasp. In ranged there's: Time Slowdown, Charged Ranged, Lightning Hold, Rapid Lightning, and Tornado. For defense we've got: Block Counter, Dodge Counter, Dodge Invulnerability, Speed Heal, and Electric Shield. In the speed branch we have: Cardio, Speedier Burst, Regenerate, Enhanced Inhaler, and Overcharge. And lastly in the ultimate branch is: More Time, Fast Recharge, More Damage, Lightning Storm, and Unlimited Power. Next, I'll be working on actually creating all of these skills and abilities in-game.