Continue to develop this game and you have at least 1 player :P
I enjoyed my fair share of Roblox tower defense games but I do not think you have a copyright issue at hand here.
I must ask though are those your own assets that you are authorized to use? If so all is well. If not, change them later to not have licensing issues. I think a tower defense game of this type is missing from the Steam store and people would probably play it -if marketed to a relevant audience. Good luck!
The only thing i didn't make can be found on this website https://assetstore.unity.com/packages/3d/props/guns/low-poly-weapons-vol-1-15198...
Free low poly weapons vol.1. It's very good for what it is and has some variety, but everything else is pretty much mine. That shouldn't be a problem with the game getting copyrighted i think. Also, there is some music on youtube i found for the game because i can't make music no matter how much i try. But it's most likely not gonna be released with music, because i won't be able to pay anything if something happens and i don't wanna risk it. There are also some free assets made by unity when it came to making skyboxes, some textures and some particles but that's just a part of the unity engine.
