So, the very first thing that I'm going to do is qualify myself. I've worked in controls and engineering for 20 years and am intimately familiar with wiring components and circuitry. This is not a puzzle game in my opinion, this is an educational game through and through and is the absolute best primer to basic electricity that I have ever seen. I've actually forced one of my techs who was interested in finding an actual electricity based game to play. If there's graphic defects, I didn't notice. But I did appreciate all of the thought that went into the concepts and the emphasis on pedagogical methods for reinforcing topics. Well done! I would love to see a furthering of the concept with capacitance and inductance as well.
Poison tower doesn't give ya money when the poison kills an enemy! Other than that, an interesting blend of global upgrades as well as individual tower upgrades.
Thank you for the nice comment.