Released in 2010, System Protocol One is a network security themed tower defense game. The graphics are what you would expect from a game with this theme. This day and age, there is a proverbial flood of tower defense games available. In the now tiring genre of tower defense, this game does little to set it self above the rest and while it does have a few unique aspects in my opinion it's ultimately not worth playing.
One notable issue I had with the game was pacing. The tutorial was a painful bombardment of game mechancis; unlike Defense Grid, which paces various mechanics over several levels so you can get familiar with them, this game slams you with all of them at once and throws you into game to engage in a trail and error process of figuring it all out. I have also noticed issues with the difficuty pacing where certain waves will drastically increase in difficulty.
I digress, but as a systems administrator, I felt like the developer could have done something more clever with the conept of "maintaining uptime" while "securing the network", as hinted in the tutorial. Sadly it seems the only implentation of this concept is the need to keep at least one open path.
The game does have some unique aspsects, and if you like tower defense games you might appreciate this game. However if your are more or less neutral towards these sort of games there are better options available if you are in the mood for tower defense.