This build is OUTDATED. This means you will have to improvise to make it work. Builds are outdated when Power Pills (or Free Pills) are included in the strategy. Free Pills have been removed from the game because players stacked the pills with Power Pills Turbo.
Must Haves: Chainsaw Addon, Enhanced Muscle Fibers (EMF), Electrifier, Med-i'-can, Piggy Bank, and Power Pills (Free)
Other Helpful skills: Basic AI Chip, Aggressive AI Chip, and Blow Up Doll
Buy Order: Piggy Bank > Power Pills > EMF > Electrifier > EMF > Electrifier > Med-i'-can x 2 > Chainsaw Addon x 3
Alternate Order: Piggy Bank > Power Pills > Electrifier > EMF > Med-i'-can > Electrifier > EMF > Chainsaw Addon x 3
This is a very aggressive build and can be dangerous if you get too overzealous. The key to winning with this build is to be aggressive while keeping an eye upon your surroundings and health.
To begin, purchase the Piggy Bank, Power Pills (Free version), EMF x1, and finally Electrifier x1. Having these will place you in a really good position to dominate foolish opponents. You won't have stealth with this build until late game, but don't worry as this build won't need it. What you will want to do is focus on lone targets and aggressively assault them. When your health drops to 50-30%, run unless you are certain that you can defeat your opponent; remember, DON'T get overzealous. Gather health restores whenever needed and repeatively greave the opponents in single combat. Once you have built up enough (at least 195 to 355) solar, quickly return and buy Electrifier (final upgrade) and EMF (final upgrade). Now you will be even more aggressive, allowing you to further tear into opponents. Once you have either 150 or 300 solar, return to buy Med-i'-can to full upgrade. From this point, focus upon purchasing all the upgrades for Chainsaw Addon to maximize the damage output for Leon. For more devistation, buy Stealth followed by Aggressive AI Chip for immense damage output once you have finished the previous purchases.
Important notes: If your opponents are dishing out too much damage early on, follow the Alternate build and buy one Med-i'-can upgrade before purchasing the final upgrades for EMF and Electrifier. This will make Leon harder to kill early on. if you are daring, don't purchase the Med-i'-can upgrades until you have bought 2 Chainsaw Addon upgrades.